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 its 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.