To understand what the solutions to climate change are, we need to understand first what is going on. Despite the feeling of our time that science has already answered most questions about our planet, hurricanes and ecosystems, we still have a lot to learn about the dynamics of our world.  Not only do we need more explanations, but we also need to apply those findings to real life and real projects. That is the work of the Crowther Lab, a research group created in Zürich, Switzerland. We have met with the head of the laboratory Tom Crowther, to discuss the potential of science and data for sustainable projects fighting climate change.

Hi Tom, thank you for answering our questions! Can you explain to us the purpose of Crowther Lab and how it came about?

The Crowther Lab was formed at the end of 2017 and is part of ETH Zürich, the world’s leading University in Earth and Environmental Sciences. We are a team of 15 researchers from Earth scientists, remote sensing experts, community and ecosystem ecologists, programmers, biochemists, to molecular biologists – just to name a few. We’ve come together with one goal in mind – to generate a better understanding of how Earth’s natural systems work, how they are affected by climate change and, most importantly, how we could use these natural systems as a tool to help mitigate climate change and biodiversity loss, something we refer to as “nature-based solutions”.

Our lab is divided into four key research areas, which are the basis of our approach to assessing and guiding the effectiveness of nature-based solutions.

Our ecologists analyze local scale mechanisms to understand more about Earth’s fundamental ecology, to try and explain for example why there are there so many living organisms in Earth’s ecosystems and how they are able to operate as a community. Using the latest developments in machine learning and AI, the findings gathered from this fundamental research are correlated to climate and geological data-sets to create global maps which reveal how these fundamental mechanisms behave across the entire globe.

By observing Earth’s ecology on a global scale, we are able to understand how global ecosystems will change in the future and research how to most effectively address climate change and biodiversity loss through nature-based solutions. This ability to understand and address climate change is the motivation behind everything that we do.

This four-pronged approach, together with our global data-sets, is exactly what makes our lab unique. With such a unique mix of scientists, working across specialisms to analyze such high-resolution data, we are able to directly impact the effectiveness of restoration projects around the world. Working as the advisors to the UN’s trillion trees campaign, we put our findings into direct action, helping many restoration projects around the world to set effective goals and target the best regions and strategies for effective carbon capture in Earth’s ecosystems.

Can you tell us a bit more about Global Ecosystem Ecology? Do you think it is important to think holistically rather than focus on particular issues to successfully fight climate change?

Climate change and biodiversity loss are among the two greatest threats facing society – and they are intrinsically linked. Historically, classification of global ecosystems was based purely on top-down satellite imagery. Whilst satellite data has transformed our capacity to classify terrestrial ecosystems across the globe, providing a resolution down to 3,7 meters, which is sharp enough to distinguish individual trees, they cannot tell us what’s going on below the canopy surface.

The Crowther Lab was founded with the understanding that it is only with a global perspective of all ecological ecosystems, be they below or above ground, that we can define effective targets and strategies for nature-based solutions. Our lab is enhancing climate predictions with the largest set of ground-sourced data – over 30 million measurements of individual trees as well as 120,000 measurements of soil communities around the world – collected through a global network of ecologists. The maps we develop provide critical layers of never before seen ecological data for both for the above and the below-ground world.

Fight Climate Change with Data

The Crowther Lab is a multi-disciplinary research lab divided into four key areas to define effective nature-based solutions. (Credit: Crowther Lab)

Whilst there are many particular issues and approaches to fighting climate change, we believe that generating a holistic understanding in the first place will be the most important step in ensuring the success of these approaches. For example, it is well known that planting trees, due to their ability to draw carbon from the atmosphere, has an overall cooling impact on the climate. However, in some places dark coloured trees actually absorb sunlight and warm the climate around them. Our holistic approach to mapping the global forest system is helping us target the right areas to plant new trees.

You succeeded in developing and using a new method for calculating the quantity and density of trees on the planet. How is this map currently helping in directing the reforestation efforts worldwide?

Throughout the 20th century, there have been various international level reforestation campaigns as humans have become increasingly aware of the importance of trees in maintaining biodiversity and providing critical ecosystem services such as water and air filtration, soil nutrient cycling, maintenance of wildlife habitat etc. However, these different campaigns may have been lacking clear, coordinated goals. The global tree density map we created provides a central point of reference for reforestation efforts across the world.

Current tree cover versus potential tree cover

Current tree cover versus potential tree cover (in yellow) (Credit: Crowther Lab)

The best example of this is the UN’s billion tree campaign, managed by Plant-for-the-Planet. With the knowledge that there are 3.04 trillion trees already on Earth, they realized their target to plant 1 billion trees wasn’t going to have the magnitude of the impact they hoped for. As a result, they redoubled their efforts with a new target to plant 1 trillion trees. The high-resolution nature of this map means that it can also inform local and national-scale efforts.

For example, in Costa Rica, where our map has helped to inform the Bellbird biological corridor project – aimed at restoring forests to support local biodiversity. By using our map, they were able to identify how many trees could be supported in their region of interest. This information did not only serve as a practical guideline, but it also allows them to place their restoration efforts into a global context by showing the proportional contribution of their efforts, relative to the existing forests in that area. At all scales, this information can provide a valuable tool for establishing meaningful goals and evaluating the impact of their efforts.  

Is there some macro-area which is particularly appealing for a mass replantation of trees due to its good land conditions and sparse or little human presence?

Generally, tropical regions are the environments that support the fastest tree growth. These areas capture and store the largest amount of carbon and they contain the greatest proportion of global biodiversity. Restoration in all tropical regions should be a global priority for addressing climate change, biodiversity loss and enhancing all of the services that forests provide to humans. 

Read also: Deep Dive into Ecosystem Services

In contrast, forests in higher latitudes capture a smaller amount of carbon. However, the carbon storage in the soil below these temperate and boreal forests is far greater than in the tropics, so the value of high-latitude forest restoration is in the sequestration of carbon to the soil.

At a global scale, we need to focus our efforts on conserving old growth forests all over the world. Any forested regions that contain old growth forests store huge amounts of carbon and biodiversity. The loss of these ecosystems is not only a travesty for global biodiversity, but will also accelerate climate change. 

Which are the tree species that are particularly good in terms of capturing CO2 in certain areas?

In Europe, for example, spruce and pine species absorb carbon the fastest in order to fuel their growth – but this is only part of the whole story. Our research shows that if you were planting, say 100 trees, a mix of many different species would store more carbon in the overall ecosystem than just planting one type of species. What this means is that if the world’s forests were reduced to monocultures of a single species – even the most productive species – carbon storage would be decreased by over 15%. In monetary terms, this could reduce the value of the timber industry from $616bn to $300bn per year (ed: €543 Bn. and €264 Bn respectively). 

How much is a species worth to the world?

An example of monetary valuation for ecosystems and single species. (Credit: Crowther Lab)

Another key aspect to highlight is the importance of soils in capturing carbon from the atmosphere.  Whilst tropical forests store the most above-ground carbon, boreal forests have a far greater capacity to store carbon within the soils below them. Both aspects – the potential of carbon capture in trees and in soils – show the importance of biodiversity to combat climate change.

What does this mean exactly? Are trees the alpha and omega of climate action? Can trees save the planet?

The short answer to this specific question is: no – but the reason why may not be as straightforward as you think. Our research has shown that the Earth is home to just over three trillion trees, naturally forested regions could increase this number by 700 billion to 1.3 trillion. But, at the same time, 15 billion trees are cut down each year, making human interference the strongest control factor of tree abundance and the global carbon household.

The same principle is true for other natural ecosystems. We are now, for example, starting to understand an even bigger carbon pool than tree biodiversity – the soil. As global temperatures rise and the soil warms, a predicted 55 gigatons of carbon stored in the Earth’s soil could be emitted into the atmosphere – roughly the equivalent to the annual carbon emission of the U.S. This enhanced soil carbon loss could accelerate climate change by up to 17%. What is important to understand is that all these ecosystems influence one another and are further impacted by human interference. There is no one-size-fits-all answer, it is rather – again – the holistic view that will provide the necessary answers.

In a nutshell: Although trees play a vital role in the regulation of our carbon household, seen only individually they are not the solution. Rather, we should focus on entire forest ecosystems, which we believe to be our strongest weapon in the fight against climate change.

What are the next steps for the Crowther Lab in 2019?

At the Crowther Lab, we strongly believe that global models, pairing top-down satellite with bottom-up ground-sourced data and compiling these to spatially-explicit information in the form of interactive maps, is the next generation of ecosystems science. These maps not only inform us about current ecological diversity, but we are now starting to generate an understanding of the ecological potential, e.g. how much forest and carbon could be supported on the planet, at both global and regional scales. We hope this will provide the scientific basis to guide restoration and conservation organizations which parts of the world we should focus on and with what activity if we are going to address one of the greatest threats to modern society.

“We are now generating the scientific basis to support our most firmly-held belief that, by restoring Earth’s ecosystems and preserving existing biodiversity, we can definitely slow, if not stop, the progression of global climate change.”

Specifically, there are three important launches planned for 2019:

  1. Reforestation potential map – We will publish research mapping how the distribution of forest types will change over the next 10 to 30 years. This map will also reveal, the climate impact of reforestation in any region of the world.
  2. Soil carbon storage – Additionally, we will be releasing research which maps soil carbon storage potential across the globe, highlighting the massive potential of soil restoration to sequester huge amounts of carbon from the atmosphere. 
  3. Biodiversity datasets – Lastly, we will make 30,000 measurements of trees and 1.2 million measurements of soil available through our Global Forest Biodiversity Initiative and Global Soil Biodiversity Initiative.

What does it mean to you personally to be a scientific enabler in the fight against climate change?

For too long academic scientists have been too disconnected from politicians, conservation organizations, and vice versa. As a result, we have many examples where a poor understanding of the local ecosystem has meant restoration efforts have been ineffective or even damaging. It’s fantastic that both sides are now coming together and we are able to partner with organizations like Plant-for-the-Planet and the FAO to ensure we maximize the effectiveness of reforestation efforts in the limited time and resources that are available. It would bring great pride if my team and I can play even a small part in allowing Earth’s natural biodiversity to flourish in combating climate change.

Finally: What would you say to a young mind who wants to get involved in climate change but feel disheartened by the size of the problem?

Don’t be disheartened. Although I understand how the magnitude of the challenge can seem insurmountable for the individual, one must not forget that climate change is anthropogenic. It is human action that drives climate change and it is human action that can mitigate its effects. There are so many examples of what one could do: converting to a plant-only diet, for instance, could save 66 gigatons in carbon. If you want to go even further, our research is showing how the simple act of planting trees and restoring ecosystems can have a huge cooling impact on our climate. We are now generating the scientific basis to support our most firmly-held belief that, by restoring Earth’s ecosystems and preserving existing biodiversity, we can definitely slow, if not stop, the progression of global climate change.

Thomas Crowther is a professor and head of the Crowther Lab, an interdisciplinary research group with a team of 15 scientists that all work with one thing in mind – the climate. The Crowther Lab was established in 2017 and is part of ETH Zürich.


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