A Massive Global Reforestation Project Is How We Fix Climate Change

We can conclusively solve our climate change problem with a massive global reforestation campaign. This piece is a quick 2-minute summary, go here for a more in-depth overview with technical details.

Here is how:

First, the basic unit of CO2 is a “ton.” A billion tons is a gigaton. Each year, the world emits about 45 billion tons, or 45 gigatons of CO2.

We know that forests absorb CO2. How much? An acre of forest absorbs about 15 tons of CO2 in a year. Other tree species absorb somewhat more or less, some of them a lot more.

This means we need 3 billion acres of forest to offset our entire worldwide CO2 emissions each year.

Does the world have this much land for new forest?

Yes, but we will need to regreen deserts. There are about 4.7 billion acres of desert available, and we’ll only need about 3 billion of that. People have been successfully regreening deserts for decades, e.g. in China, Jordan, UAE, and Israel.

The limiting factor to regreening a desert is irrigation. We have to irrigate the trees for about 20 years until the vegetation changes the climate and induces its own rainfall.

We cannot rely on existing freshwater supplies, as they are all spoken for (food, agriculture, etc), so the only other source is desalination of seawater. This is energy-intensive, so our energy sources need to be low or zero-carbon —solar, for instance.

On a per-acre basis, the cost to build a solar array sufficient to power the desalination needed to irrigate that acre of forest for 20 years is about $1000/year per acre.

Thus, to reforest 3 billion acres at current prices will cost the world an investment of $3 trillion/year for 20 years.

That sounds like a lot, but the world GDP of 2017 was $80 trillion.

Therefore, this plan would require an investment of a little less than 4% of world GDP every year for 20 years. Combined with even moderate and gradual reduction in fuel emissions, we would effectively offset all CO2 emissions within 20 years once the forests reach maturity.

If we were to reforest the remaining 1.7 billion acres, the excess sequestration capacity would remove all of the CO2 remaining in the atmosphere that we have emitted since 1750 (beginning of the Industrial Revolution) in under 35 years.

This geoengineering plan is the lowest-cost, lowest-risk, most politically feasible, and requires the least risky technology to accomplish.

It is the solution most likely to work, and the only question is how long we will wait until we implement it.

For more information:

Your question may be answered in the list of Frequently Asked Questions

A much more complex overview with technical details

Our cost-validation pilot project in Hawaii

Existing reforestation efforts

Existing science that supports or advocates massive global reforestation as the best solution to climate change

Reposted from Medium: https://medium.com/@yishan/a-massive-global-reforestation-project-is-how-we-fix-climate-change-36afc6d4dc2

Frequently Asked Questions

For A Massive Global Reforestation Project Is How We Fix Climate Change

Why don’t we just / isn’t it better to reduce fossil fuel emissions?

We do need to reduce fossil fuel emissions, but that is only half the solution. If your house is a mess, you need to do two things: 1) stop making more mess, and 2) clean up the mess. Reducing emissions is #1, and this plan is #2.

Most efforts today are focused on doing #1, and they’re right to do so. But there are two main obstacles:

  1. An immediate cessation of all fossil fuel emissions would cause a worldwide economic collapse, and leave us with no capacity to undertake any significant activity.
  2. Taking emissions immediately to zero would still leave all of the current CO2 in the atmosphere, and continue to warm the planet. This is likely to still cause ice melt, environmental degradation, extreme weather patterns, and lots of other problems. Having collapsed our economy, we would be helpless to fix any of them.

Realistically, curbing emissions is very hard (how much progress are we seeing? Let’s be honest). Even extremely ambitious plans in very environmentally-conscious countries only aim to reach net-zero goals by 2040 or 2050: only at that point would the increase in CO2 in our atmosphere begin to level off.

We need to have a solution to remove large amounts of CO2 from the atmosphere itself by or before that time. Massive global reforestation is that solution.

Optimistically, we hope that governments and economies make progress in curbing emissions while we begin reforesting 3 billion acres of trees and we meet in the middle. Maybe we’ll only need to reforest 2 billion acres.

If it’s so simple, why hasn’t someone thought of this plan before?

Until very recently, it was not economically viable.

Desalination requires significant amounts of energy. Desalination plants in the past were mostly powered by coal or gas, meaning enormous amounts of CO2 would be emitted for every gallon of freshwater produced, thus offsetting most or all of the benefit of replanting forests using such water.

Reforestation experts around the world have known for decades that forests are the cheapest and most reliable way to sequester CO2. But large-scale conversion of deserts into forests wasn’t possible due to a lack of freshwater supplies, and the high cost of renewable energy prevented us from desalinating seawater on a large enough scale.

However, in 2018, something really important happened: the cost of solar power dropped to a level where desalination plants can now be affordably powered entirely via solar. Large-scale desalination can now be accomplished with an extremely low carbon footprint.

We now have the chance to do what couldn’t be done before: create 3 billion acres of new forest for less than 4% of world GDP annually, which will offset all of our emissions and begin to remove excess CO2 from the atmosphere.

It is now cost-effective to terraform the planet and fix our climate problems.

What about olivine / limestone weathering?

Olivine weathering is a method of accelerating the natural process of CO2 absorption into limestone. It is a promising method of sequestering CO2.

While it is fairly simple in conception, it does face a few hurdles:

  1. Its action is somewhat secondary: oceans absorb CO2 and become acidified, and the olivine helps re-absorb this CO2 from the ocean. It de-acidifies the ocean so that the ocean can absorb more CO2.
  2. It requires the excavation of very large amounts of olivine (billions of tons), crushing it into appropriately-sized sand and gravel, and then shipping it to select shoreline locations. This is extremely energy-intensive (i.e. large machines need to excavate, crush, and haul to shorelines) and those machines are not as easily electrified, so certainly at first it would result in large carbon emissions.
  3. There are likely to be political and ecological objections to spreading olivine on the tropical beaches and shorelines areas where it would be most effective.

Despite these hurdles, it is still a method worth investigating. For more information about, please visit Project Vesta.

One smaller-scale version of this plan is to spread the olivine near or around coral reefs. It has been found that the de-acidification effects are highly localized, and could act as a stopgap measure to preserve coral reefs in the short term. This requires much less total olivine excavation, but could have outsized beneficial effects on preserving coral reefs and the biodiversity they represent.

Isn’t it a better idea to stop deforestation?

It is an extremely good idea to stop deforestation.

That said, stopping deforestation doesn’t get us 3 billion additional acres of trees: we need to be creating more CO2 sequestration capacity on top of what we have.

However, every acre lost is another acre we need to make up, so it is incredibly important to stop deforestation. It costs a lot more to re-grow an acre of new forest, compared to not-cutting-down an existing acre.

Very roughly speaking, we lose about 15–20 million acres of forests a year to deforestation. It would definitely save a lot of work not to have to reforest those 15–20 million acres.

Why do we have to regreen deserts? Why don’t we just plant trees elsewhere?

First, let’s define afforestable land to be land where 1) there isn’t already desert and 2) doesn’t need to be regreened in order to plant new forests. We will call deserts that require regreening to be “reforestation.”

There isn’t enough afforestable land to comprise 3 billion additional acres of forest. This might be grasslands, degraded cropland, recently-cleared forests, and other area in temperate or tropical rainfall climates where trees can thrive if planted and don’t require ongoing irrigation.

According to various estimates, there is somewhere between 900 million to 1.08 billion acres available for afforestation, not taking into account whether that land is privately owned or currently occupied by habitation. This falls short of the 3 billion acres that we need.

Moreover, the owners of that land may not allow us to use it, or simply don’t want it be reforested. If they do, that’s good because every acre of new acre of new forest that does not need regreening via desalinated seawater can be planted for about 1/10th the cost.

However, we have made our cost estimates based on a worst-case scenario where all of the land for reforestation has to come entirely from regreened deserts.

If we were able to get 1.08 billion acres of new forest from the above afforestable land, it would reduce total costs by roughly $900 billion/year over the 20 year period.

Does planting trees change the albedo of the land?

Yes, it does, and it is a significant complication.

In certain areas, planting new forests changes the albedo of the land such that the increased heat absorbed offsets the cooling effects of the CO2 sequestered by those forests. The best research seems to suggest that these areas are mostly boreal (northern) regions, such as land in Canada and Russia. The reason is because those areas often covered in snow (light-colored) and forests are darker-colored.

Unfortunately, those areas comprise about 300 million acres that are counted in the estimates of total afforestable area mentioned earlier, so the real acreage of land available for afforestation is actually quite a bit smaller — only about 600 million to 708 million acres — another reason why we make the safer assumption of regreening deserts.

Don’t we have freshwater shortages? How can we water all those trees?

Correct, we cannot water the new forests using existing freshwater supplies. The amount of available freshwater worldwide is very limited and already spoken for: it’s needed for human consumption and agriculture.

To irrigate 3 billion acres of new forest, we need to utilize a new and separate supply of freshwater that doesn’t compete with existing supplies: desalinated seawater.

Isn’t desalination extremely expensive or energy-intensive?

Yes, desalination is quite expensive, primarily because it is very energy-intensive.

However, coupled with low-carbon renewable energy sources, it is the only way to source the large amounts of freshwater we need. While it is expensive, it is not prohibitively expensive: many countries and municipalities use it to create freshwater for human consumption from seawater, and we can use it to irrigate our new forests.

Desalination is actually ideally suited to intermittent renewable power sources like solar and wind. One of the biggest drawbacks to solar and wind when used for most residential or commercial usage is that the generated energy needs to be stored for nighttime usage (or other times when the sun isn’t shining or the wind isn’t blowing). This requires expensive batteries, which comprise the majority of the cost for solar and wind farms. But with desalination, we can simply desalinate water when power is available (e.g. during daytime sunlight) and store the freshwater in storage tanks for irrigation around dusk or whenever appropriate. In essence, we can exchange expensive batteries for inexpensive water storage tanks. Early numbers from our cost-validation pilot project indicate that we may see savings of up to 33% when compared to typical solar-backed utility grids.

Doesn’t desalination dump a bunch of effluent that’s bad for the environment?

Background: when desalinating seawater, you take two gallons of seawater and filter it so that you get one gallon of freshwater and one gallon of double-salty water (“effluent”).

The environmental effects of desalination effluent are unclear. On the one hand, most of it is just the same stuff that was in the seawater in the first place (i.e. mostly salt, some organic material). On the other hand, concentrating it all in one place might still be bad.

That said, desalination for the purposes of freshwater irrigation has certain advantages that greatly mitigate potentially negative effects of it effluent.

First, desalination plants that need to produce freshwater fit for human consumption must treat the water with chemicals to reach a higher standard of cleanliness. This increases the amount and variety of chemicals that potentially make it into the effluent. Desalinating seawater to irrigate plants requires none of that: we’re just removing salt. If the water still has some microorganisms in it, that’s fine: we’re pouring it on plants, not drinking it! Likewise, the effluent is just salt that was originally in the seawater, and no additional chemicals. It’s no more dangerous than the salt that typically builds up on coastlines from the ocean.

Secondly, Mother Nature offers us a trick to desalinating seawater that both increases efficiency and reduces the salinity of the effluent. Instead of sourcing water directly from the ocean, you drill a shallow well a few hundred feet from the ocean until you reach brackish water. This water is seawater that’s seeped inland into the earth, but the process of doing so results in water with lower salinity (“brackish”).

We’ve done exactly this at our cost-validation pilot plant, and the brackish water is only about 25% the salinity of seawater. The well is continually replenished because it’s fed by ocean water — it’s sort of like digging a hole in the sand at the beach until you reach water. Desalinating this brackish water uses less energy and the effluent is only 50% the salinity of seawater: twice that of the input water but still much less salty than seawater.

It turns out that trees exist that tolerate (or even thrive) in seawater, so this effluent can potentially also be used to irrigate just as many additional acres of saltwater-tolerant forest. At our pilot project, we have actually been able to use the effluent to regreen more parts of the land. Thus, it’s quite possible that our true water output available for irrigation is double that of original calculations, if half of our forests are comprised of saltwater-tolerant trees. However, because we haven’t confirmed and quantified this aspect completely and it’s not clear if saltwater-tolerant forests are compatible with all ecosystems, we don’t include this “bonus forest” in our top-level calculations.

Can we just find the fastest-growing species of tree and plant tons of those?

In theory, yes. In practice, reforestation is a bit more complex.

Reforestation is really shorthand for “rewilding,” which is the process of rendering land back to a “wild” state of greenery. The reason it’s reforestation is because rewilding often starts with the planting of an “anchor tree” species, a tree upon which many other species (of bacteria, insects, and other plants) in the area depend on and use to thrive.

When doing this, we typically want to select from among the region’s native tree species, because the ecological web in that area supports an order of magnitude more species of such dependent organisms: bacteria, insects, grasses, shrubs, and other animals. Non-native species don’t have this. With native plants, it’s literally 10x more species. All of those species represent carbon sequestered, and it’s this additional mass of carbon that is the real ongoing carbon sink. It’s all of the life that grows up amongst the new forest that sequesters carbon.

Thus, in the long-run, it’s unlikely to be advantageous to take the fastest-growing species of tree anywhere in the world and simply plant monoculture plantations of them worldwide. At best, you might select the fastest-growing tree native to that region, but a more in-depth understanding of the area’s ecosystem might lead us to select a species that most effectively facilitates the regeneration of an entire ecosystem.

What’s the fastest growing species of tree?

Since the definition of “fastest-growing” is subject to debate, one of the fastest-growing species of tree is a subspecies of Eucalyptus tree, which can potentially sequester up to 50 tons/CO2/acre per year.

Unfortunately, while this might seem ideal, it doesn’t work very well in practice: Eucalyptus is native only to Australia, and is allelopathic, which means it produces chemicals that suppress the growth of other organisms around it. This inhibits the growth of a surrounding ecosystem of plants and even animals. You’ll get a bunch of fast-growing trees, but nothing else.

How do we get governments on board with this?

The same way we get governments on board with anything: we vote for it, and put people into office who understand and want to execute this plan.

One of the advantages of this plan is that it does not require getting any one particular government on board: it is a distributed effort that can be undertaken by people worldwide. Time and effort don’t need to be wasted convincing those who don’t want to be convinced.

Is there any other research on this subject?

There is. Other scientists and groups are beginning to understand the possibilities inherent in truly large-scale reforestation. Check out:

Feb 2019: Massive restoration of world’s forests would cancel out a decade of CO2 emissions, analysis suggests (Actual PDF paper and supplemental data)

Apr 2019: Restoring natural forests is the best way to remove atmospheric carbon (Actual PDF paper)

Aug 2019: We Already Have the World’s Most Efficient Carbon Capture Technology

As far back as 1991, Norman Myers and Thomas Goreau published a paper suggesting that a program of large-scale tropical reforestation would significantly counter the greenhouse effect: Tropical Forests and the Greenhouse Effect: A Management Response

What about the Bonn Challenge?

The Bonn Challenge is the heretofore largest global effort to unify all reforestation commitments across the world. It has recorded commitments from countries to restore 150 million hectares (370 million acres) by 2020 and 350 million hectares (860 million acres) by 2030.

If the reforestation commitments made in the Bonn Challenge are all fulfilled, it will go a long way towards a global plan to reforest 3 billion acres.

Reposted from Medium: https://medium.com/@yishan/frequently-asked-questions-bbabfc5a6ba

Our Project in Hawaii

In considering large-scale strategies to fix climate change, it turns out that the lowest-risk, lowest-cost, and most politically feasible strategy is the massive global reforestation of 3 billion acres.

To concretely prove out key technologies and costs, we have recently completed construction of the world’s largest fully off-grid 100% solar-powered desalination facility. There are other larger desalination plants, but they are all grid-tied and/or reliant at least partially on fossil fuels. In contrast, we are completely independent and 100% powered by solar energy.

Our facility comprises a half -acre of solar panels rated at roughly 128 kW total generating power and 300 kWh of battery storage. It is designed to produce 128,000 liters/day (34,000 gallons/day, or 128 m3/day) of freshwater, more than enough to irrigate the entire property. The facility is off the grid, so we have created our own electrical and water utility.

Recent cost improvements in solar mean that green desalination is now feasible. The significance of this cannot be understated, because desalination is uniquely suited to using solar power, as it avoids the solar intermittency issue.

The area of North Kohala where our project is located used to be covered with an ancient sandalwood forest, from the mountains to the shore. Hundreds of years ago, the entire forest was cut down to supply the profitable sandalwood trade and the region never recovered. It remains a desert to this day.

As of December 2019, we have been working on this project for about 2 years and have reached the final phases of full system-wide integration testing. We’ve produced hundreds of thousands of gallons of freshwater and begun to regreen the surrounding land, and have begun the planting of anchor tree species. Our facility is located on the Big Island of Hawaii, where the freshwater now enables us to begin restoration of the lost sandalwood forests on the western slopes of the Kohala region.

Biomes are self-sustaining. If you deforest a region and make it a desert, it stays a desert. If you reforest a region, it will actually sustain itself too: plants cool the atmosphere and bring water. This means that if we can reforest a region and irrigate it until the trees are mature, we can re-create a self-sustaining forest.

Our project is just a small beginning within the entire North Kohala region. Successfully reforesting this part of it would show that it can be done — not just here, but in deserts and other marginal land around the world.

There have been many projects over the past few decades where determined individuals or communities were able to reclaim a desert. The technologies we are employing here demonstrate a full end-to-end system that can be replicated worldwide.

Reforestation aided by solar-desalinated irrigation is likely to be the lowest-cost and lowest-risk method of mitigating or reversing the effects of climate change at scale. It can be done by communities and people everywhere, and in a very decentralized manner.

If you are in the area and would like to drop by for a tour or have any questions, please contact us at info@terraformation.com.

Reposted from Medium: https://medium.com/@yishan/our-project-in-hawaii-4c6c5a6052d7

A Massive Global Reforestation Project Is How We Fix Climate Change

An In-Depth Overview of Key Technical Factors

Go here if you are looking for the easy 2-minute high-level summary instead.

Most geoengineering strategies focus on employing an array of exotic technologies or speculative scientific breakthroughs. However, seriously surveying the proposal geoengineering strategies [link] to reduce and reverse CO2 levels in the atmosphere reveals that almost all of the proposals are risky, both in terms of whether they will succeed and whether they could have negative unforeseen side-effects. Many are also prohibitively expensive, and large projects with significant unknowns usually have massive cost overruns.

However, one strategy turns out to be low cost, low risk, politically feasible, and can be implemented in a distributed manner by countries, corporations, communities, and individuals all over the world using relatively low levels of proven technology.

This strategy is the massive global reforestation of around 3 billion acres of land.

Tree-planting is old news. We’ve heard from environmentalists and hippies that planting a tree is good for the planet. It’s low-tech, it’s boring and dull, it’s not shiny and cool. We often imagine that if we can just come up with a clever new machine, it’ll solve our climate change woes.

The key issue is that when solving extremely large-scale problems, the basic “unit” of your solution must be very simple and low-cost, because all of the cost and complexity comes later, when you’re trying to do that basic unit a billion times. Scalability imposes its own unique technical challenges.

The key idea here is that while planting a single tree, or even a single forest, won’t put a dent in the problem — it turns out that there is a number of trees that WILL solve the problem. It’s very large, but it turns out it’s both do-able and affordable.

That number is 3 billion acres of trees.

Here’s the Math:

First, the basic unit of CO2 is a “ton.” A billion tons is a “gigaton.” Each year, the world emits about 45 billion tons, or 45 giga-tons of CO2.

This amount is rising by about 7.5% a year, but let’s focus on the 45 gigatons for now.

How much CO2 does an acre of forest absorb in a year? It turns out that a 50-year-old oak forest absorbs 15 tons of CO2 in a year.

This means we need 3 billion acres of mature forest to offset our annual CO2 emissions.

Pretty simple, but 1) we need to make sure we have enough land for that and 2) trees need water.


According to Drawdown.org, the total available land available for tree-planting is about 1.08 billion acres. That’s not quite enough. But, Drawdown’s number refers to the amount of land available for afforestation, which is the replanting of trees on land where there used to be trees but where they got cut down (“degraded grassland, cropland, and forest”).

What if we could find more land?

It turns out that on Earth, there are 4.7 billion acres of desert.

Can we reforest desert? It turns out that we can. There are numerous projects where barren lands have been reforested — for example in SpainJordanIsrael, and China. The latest example is the Kubuqi Desert in China, which reclaimed 1.4 million acres from the desert through reforestation. Small-scale projects have been successfully reclaiming land from the desert for decades. Now we need to do it at a massive scale.


Upon being planted, trees need a lot of water to get established, and then (if in desert regions) require irrigation for about 20 years. This ongoing irrigation is the main cost of reforestation. Is it affordable? It turns out the answer is yes, even in worst-case cost scenarios.

Because the world is already facing freshwater shortages, we cannot assume that existing freshwater supplies will be available for irrigating our massive reforestation project (existing water needs to be available for people and agriculture). Instead, the only way to guarantee a steady supply of freshwater is through desalination.

Desalination is energy-intensive, so we’ll need to build new energy production capability on top of what we have, and it will need to be low- or zero-carbon sources (or we are just undoing our own work). Solar power happens to be uniquely suited to this application.

Thus, we need to figure out the cost of building desalination plants, and supplying them with energy. Well, it turns out that the cost of producing 1000 liters (a cubic meter) of freshwater is about $1 at current technology/cost levels.

The yearly water requirement for an acre of trees is between 500–1000 cubic meters. Let’s take the higher figure.

This means that watering 3 billion acres of forest will take 3 trillion cubic meters of water a year, and at $1/cubic meter, that’s $3 trillion/year.

Can we afford it?

Yes. The world GDP in 2017 was about $80 trillion.

The one-time cost of initially planting each acre also happens to be around $1000/acre (based on the cost of the latest large Chinese projects), so we would anticipate a one-time cost of $3 trillion, and then subsequent ongoing expenditure for irrigation of $3 trillion/year for 20 years.

This is only about 4% of the world’s GDP, and it’s actually a worst-case estimate.

It makes very conservative assumptions:

  • All 3 billion acres are assumed to be reclaimed desert (because none of the owners of the 1.08 billion acres want to allow us to plant trees there). Reforesting degraded land is much easier because you may only need to irrigate for about 1–5 years just to get the trees established.
  • We assume that all water used for irrigation comes from desalination. Desalinated water is literally 10x to 100x more expensive than groundwater or other freshwater sources. If any regions can spare freshwater for irrigation, the cost drops dramatically.
  • No cost savings are assumed on solar equipment or desalination technology. All of these estimates are made using current technology costs, and given current trends (as well as the huge demand that would be generated due to such a massive program), it’s very likely that costs of equipment would drop considerably.
  • All forests are new forests. Every acre of forest that we grow on land that was previously forest is cheaper to grow. Every acre of deforestation that we prevent can be counted as an acre — and it costs “zero” to simply “not deforest” an acre. In fact, not-deforesting is absolutely the cheapest way to accumulate “acres of forest” towards our target of 3 billion.
  • The original core metric of “15 tons/year of CO2 per acre of trees” derives from forestry technology of the 1970s and early 1980s, and take no account of research since then in advance plant-breeding techniques developed through Green Revolution technology for food-crop plants. In fact, as early as 1985, plantations in southern Brazil were able to boost eucalyptus tree yields potentially as high as nearly 40 tons/year of CO2 per acre.

There Are Other Significant Benefits

The Sahara Desert was not always a desert. It used to be green. Many of the deserts of the world became deserts due to the activity of ancient humans and their grazing animals.

Biomes are self-sustaining. If you deforest a region and make it a desert, it stays a desert. If you reforest a region, it will actually sustain itself too: plants cool the atmosphere and bring water. This is why we only need to irrigate our forests for about 20 years — once they reach maturity, they will influence their local biome and bring self-sustaining rains. We would be reversing not just the problem of CO2 emissions from the beginning of our Industrial Revolution, but also undoing part of the ecological changes that our ancient ancestors brought upon countless lands (don’t blame them — they were just trying to survive. But today we know better, and we can do something about it) [link]

The reforestation and reclaiming of desert would also result in a massive increase in agricultural land. The 3 billion acres don’t need to be all contiguous. Forests could be sparsely laid out in alternating agroforestry plots of forest and agriculture: the local climate changes from the nearby forest would make the intervening agriculture plots farmable, thus massively increasing food production worldwide.

It’s safer than most plans if things go wrong

Any large-scale effort will have large unintended effects. The reappearance of forests in places that have been deserts for thousands of years could affect weather and precipitation patterns. While the effect is likely to be benign and gradual as the forest mature (especially compared to the dramatically negative effects of climate change now), this solution is extremely and easily tunable: if a particular forest is found to be causing a problem, we just cut it down. Humans are pretty good at cutting down a forest.

It’s distributed and does not require global consensus

Again, any plan of this scale would normally require reaching consensus from countries around the world, which is notoriously difficult. Many plans can be held up by a single recalcitrant actor. This one isn’t. If 50% or 80% of countries decide to do it, they can move forward without the agreement of others. If some of the land needed to comprise the final 3 billion acres sits within a country that doesn’t want to participate, it can be found elsewhere.

Moreover, governments themselves don’t even need to be convinced to participate. Within any country with sufficiently well-enforced private property rights, corporations, communities, or even wealthy individuals can simply purchase or otherwise set aside land to be reforested. Any acre of land with new trees on it that can be irrigated and protected for at least 20 years will help.

Limits To This Plan

The biggest limit is that in certain areas, the change in albedo due to reforestation will cancel out the cooling benefits of the CO2 that the forests sequester. Essentially, if the land is white enough (ice and snow), changing it to darker forests (green) will result in more energy absorbed from sunlight.

Fortunately, research has been done on this already and the regions where the albedo warming would exceed cooling due to sequestering carbon have been fairly well-established. These are, basically, Canada and most of Russia. So we wouldn’t be able to do any of this in those countries — and unfortunately, Canada and Russia comprise about 300 million acres of otherwise reforestable land.

Second, we can’t simply find a species of fast-growing tree and plant it everywhere. The earliest attempts at desert reforestation in China failed because they tried to plant non-native trees. The trees that tend to do best in any region are often the native species, because millions of years of evolution have led to an existing ecology of bacteria, insects, birds, and other plants that mutually support one another and aid the optimal growth of those trees.

Therefore, every single region needs a reforestation plan specifically tailored to its unique area. Local communities are usually the most knowledgeable about these specifics, and global engagement is vital because it combines a sense of community ownership over the forest with the global mission. Community ownership is important because the forests need to be preserved for decades (actually forever), so the people who live near them must understand their significance and value.

Thirdly, local politics influence the long-term viability of this plan. We don’t just need to reforest, we need to guarantee that once planted, the forest is irrigated and remains undisturbed for at least 20 years. Areas with uncertain civil governments or rule of law make this difficult, so care needs to be exercised in deciding where to replant forests.

Existing Efforts

There have been numerous existing efforts to encourage large-scale reforestation. The most well-known of these is the Bonn Challenge, a global set of non-binding commitments by countries to regrow forests in their own territory.

Unfortunately, the total amount of forests (i.e. assuming every single country fulfilled its commitments) under the Bonn Challenge was 865 million acres, well short of the 3 billion we would need. If the reforestation commitments made in the Bonn Challenge are all fulfilled, it will go a long way towards helping this plan, but we need to do more — a full 3 billion acres.

There are also numerous non-profit organizations throughout the world dedicated to reforestation efforts, sometimes on the order of hundreds or thousands of acres. These are most valuable because they represent decades of experience across dozens of different biomes where people have successfully restored ecosystems and brought back forests. We need is to collect all of that knowledge and then do this on a truly massive scale.

How Do We Do This?

The biggest advantage of this plan is that we are already doing it. It is low-risk, the technologies involved are well-understood and accessible, and it is fairly affordable.

We just need do a lot more. Not an unattainably large amount more, but a large number: specifically 3 billion acres.

We can get that land out of degraded grasslands, croplands, or denuded forests, and we can get the rest of by reclaiming deserts.

We need the participation of not just governments, but also corporations, communities, and individuals. Anyone who can secure land and ensure that it can be irrigated for at least 20 years and protected from logging or grazing animals can contribute. However, always remember: one big advantage is that we also don’t need the participation of any one particular government, corporation, community, or individual.

We need cost improvements in solar energy generation and desalination efficiency.

The biggest risk is that this plan just isn’t seen as dramatic or fancy enough. But it will work. It is based on sound science: we know how much CO2 trees sequester, we know how to plant trees and water them, and we know how to desalinate water. Those are relatively simple things, and if we can do 3 billion acres worth of it, we will solve the problem.

As a cost-validation pilot project, we have begun reforesting 45 acres of desert on the Big Island in Hawaii, irrigated using desalinated seawater powered entirely by a large solar array.

This facility uses the latest solar and desalination technology, and concretely validates the unit costs of the technology, as well as establishes a worst-case cost ceiling: the Big Island is pretty much the worst and most expensive place to build anything. The corner of the island where we’ve located the facility gets very little natural rainfall (12-15 inches/year), so if it can be done there, it can be done anywhere.

If you want to read more, here are the details.

Reposted from Medium: https://medium.com/@yishan/a-massive-global-reforestation-project-is-how-we-fix-climate-change-e37fa24436a3