Science

Our climate projections for 2,500 show an Earth that is alien to humans

This article originally appeared on The Conversation. The post contributed the article to Space.com’s Expert Voices: Op-Ed & Insights.

Christopher Lyon, Postdoctoral Researcher, Natural Resource Sciences, McGill University
Alex Dunhill, Researcher in Paleobiology, University of Leeds
Andrew P. Beckerman, Professor of Evolutionary Ecology, University of Sheffield
Ariane Burke, Professor of Anthropology, University of Montreal
Bethany Allen, PhD student, School of Earth and Environment, University of Leeds
Chris Smith, NERC-IIASA Collaborative Investigator, University of Leeds
Daniel J. Hill, Professor, School of Earth and Environment, University of Leeds
Erin Saupe, Associate Professor, Paleobiology, University of Oxford
James McKay, Manager, Center for Doctoral Training, University of Leeds
Julien Riel-Salvatore, Professor of Anthropology, University of Montreal
Lindsay C. Stringer, Professor of Environment and Geography, York University
Rob Marchant, Professor of Tropical Ecology, University of York
Tracy Aze, Associate Professor, Earth and Environment, University of Leeds

There are many reports based on scientific research that talk about the long-term impacts of climate change, such as increases in greenhouse gas levels, temperatures and sea levels, by the year 2100. The Paris Agreement , for example, requires that we limit heating. less than 2.0 degrees Celsius above pre-industrial levels at the end of the century.

Every few years since 1990, we have evaluated our progress through the scientific assessment reports of the Intergovernmental Panel on Climate Change (IPCC) and related special reports. The IPCC reports assess existing research to show us where we are and what we need to do before 2100 to reach our goals, and what could happen if we don’t.

The recently released National Determined Contribution (NDC) assessment by the United Nations warns that current government promises set us up for a very dangerous 2.7 degree Celsius warming by 2100: this means fires, storms, droughts, floods and unprecedented heat, and deep lands and aquatic ecosystem change.

While some climate projections look beyond 2100, these longer-term projections are not factored into climate adaptation and environmental decision-making today. This is surprising because people born now will only be 70 by 2100. What will the world be like for your children and grandchildren?

To capture, plan and communicate the full spatial and temporal scope of climate impacts in any scenario, even those that comply with the Paris Agreement, researchers and policymakers must look well beyond the 2100 horizon.

After 2100

In 2100, will the weather stop warming? If not, what does this mean for humans now and in the future? In our recent open access article in Global Change Biology, we began to answer these questions.

We run global climate model projections based on Representative Concentration Pathways (RCP), which are “time-dependent projections of greenhouse gas (GHG) concentrations in the atmosphere.” Our projections modeled mitigation scenarios low (RCP6.0), medium (RCP4.5) and high (RCP2.6, which corresponds to the goal of “well below 2 degrees Celsius” of the Paris Agreement) up to the year 2500 .

We also modeled the vegetation distribution, heat stress, and growing conditions of our current major crop plants, to get an idea of ​​the kinds of environmental challenges that today’s children and their descendants might have to adapt to from from the 22nd century onwards.

Global mean near surface air temperature anomalies (solid lines) and thermospheric sea level rise (dotted lines) relative to the 2000-19 mean for scenarios RCP6.0, RCP4.5, and RCP2. 6.  Shaded regions highlight the time horizons of interest and their nominal reference years.  The lower panel shows spatial anomalies relative to the 2000-19 mean for climates 2100, 2200, and 2500 under the three RCPs.

Global mean near surface air temperature anomalies (solid lines) and thermospheric sea level rise (dotted lines) relative to the 2000-19 mean for scenarios RCP6.0, RCP4.5, and RCP2. 6. Shaded regions highlight the time horizons of interest and their nominal reference years. The lower panel shows spatial anomalies relative to the 2000-19 mean for climates 2100, 2200, and 2500 under the three RCPs. (Image credit: Lyan et al. 2021)

In our model, we find that global mean temperatures continue to rise beyond 2100 under RCP4.5 and 6.0. Under these scenarios, the vegetation and the best growing areas move towards the poles and the area suitable for some crops is reduced. Places with a long history of rich culture and ecosystems, such as the Amazon basin, can become barren.

Furthermore, we found that heat stress can reach levels fatal to humans in tropical regions that are currently heavily populated. These areas can become uninhabitable. Even in high mitigation scenarios, we find that the sea level continues to rise due to the expansion and mixing of water in the warming oceans.

Although our findings are based on one climate model, they are within the range of projections of others and help to reveal the potential magnitude of climate disruption over longer time scales.

To truly represent what a low mitigation / high heat world might look like compared to what we have experienced thus far, we used our projections and diverse research experience to inform a series of nine paintings spanning a thousand years (1500, 2020, and 2500 CE) in three major regional landscapes (the Amazon, the Midwest of the United States, and the Indian subcontinent). The year 2500 images focus on the RCP6.0 projections and include slightly advanced but recognizable versions of current technologies.

Image 1 of 3

The top image shows a traditional indigenous village before contact (1500 CE) with access to the river and crops planted in the rainforest.  The image in the middle is a current landscape.  The lower image considers the year 2500 and shows an arid landscape and low water level as a result of the decline of vegetation, with scarce or degraded infrastructure and minimal human activity.

(Image credit: Lyon et al., 2021)

The amazon

The top image shows a traditional indigenous village before contact (1500 CE) with access to the river and crops planted in the rainforest. The image in the middle is a current landscape. The lower image considers the year 2500 and shows an arid landscape and low water level as a result of the decline of vegetation, with scarce or degraded infrastructure and minimal human activity.

Image 2 of 3

The upper painting is based on indigenous cities and communities before colonization with buildings and a diverse agriculture based on corn.  The second is the same area today, with a cereal monoculture and large combine harvesters.  The last image, however, shows agricultural adaptation to a hot and humid subtropical climate, with an imaginary subtropical agroforestry based on oil palms and arid zone succulents.  The crops are tended by AI drones, with a reduced human presence.

(Image credit: Lyon et al., 2021)

Midwest US

The upper painting is based on indigenous cities and communities before colonization with buildings and a diverse agriculture based on corn. The second is the same area today, with a cereal monoculture and large combine harvesters. The last image, however, shows agricultural adaptation to a hot and humid subtropical climate, with an imaginary subtropical agroforestry based on oil palms and arid zone succulents. The crops are tended by AI drones, with a reduced human presence.

Image 3 of 3

The top image is an agrarian village scene busy with rice planting, livestock use, and social life.  The second is a current scene showing the combination of traditional rice farming and modern infrastructure present in many areas of the Global South.  The image below shows the future of heat adaptation technologies, including robotic agriculture and green buildings with minimal human presence due to the need for personal protective equipment.

(Image credit: Lyon et al., 2021)

The Indian subcontinent

The top image is an agrarian village scene busy with rice planting, livestock use, and social life. The second is a current scene showing the combination of traditional rice farming and modern infrastructure present in many areas of the Global South. The image below shows the future of heat adaptation technologies, including robotic agriculture and green buildings with minimal human presence due to the need for personal protective equipment.

An alien future?

Between 1500 and today, we have witnessed colonization and the Industrial Revolution, the birth of modern states, identities and institutions, the massive burning of fossil fuels, and the associated rise in global temperatures. If we fail to stop global warming, the next 500 years and more will change the Earth in ways that challenge our ability to maintain many elements essential for survival, particularly in the historically and geographically entrenched cultures that give us meaning and identity.

The Earth of our high-level projections is alien to humans. The choice we face is either to urgently reduce emissions, while continuing to adapt to the warming that until now we cannot escape as a result of emissions, or to begin to consider life on an Earth very different from this one.

This article has been republished from The Conversation under a Creative Commons license. Read the original article.

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