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Climate projections for 2,500 show Earth foreign to humans

Through The conversation 50 years ago

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There are numerous reports based on scientific research that speak of the long-term impacts of climate change – such as increased greenhouse gas levels, temperatures, and sea levels – by 2100. L ‘The Paris Agreement, for example, requires us to limit warming to less than 2.0 degrees Celsius above pre-industrial levels by the end of the century.

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

The recently released United Nations Assessment of Nationally Determined Contributions (NDCs) warns that current government pledges set us up for a very dangerous 2.7 degree Celsius warming by 2100: that means fires, storms , unprecedented droughts, floods and heat, and deep lands and aquatic ecosystem change.

Although some climate projections look beyond 2100, these longer-term projections are not taken into account today in general decision-making on climate adaptation and the environment. This is surprising because people born now will only be 70 years old in 2100. What will the world be like for their children and grandchildren?

To capture, plan, and communicate the full spatial and temporal extent of climate impacts in any scenario, even those who abide by the Paris Agreement, researchers and policymakers need to look well beyond the 2100 horizon.

In 2100, will the climate 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 begin to answer these questions.

We ran global climate model projections based on representative pathways of concentration (RCP), which are “time-dependent projections of atmospheric greenhouse gas (GHG) concentrations”. Our projections model low (RCP6.0), medium (RCP4.5) and high (RCP2.6) mitigation scenarios, which corresponds to the Paris Agreement target of “well below 2 degrees Celsius”. ) until the year 2500.

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

In our model, we found that global mean temperatures continue to increase beyond 2100 under RCP4.5 and 6.0. In 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 cultural and ecosystem richness, such as the Amazon basin, can become barren.

In addition, we have discovered that heat stress can reach deadly levels for humans in the tropics which are currently densely populated. These areas could become uninhabitable. Even under high mitigation scenarios, we have found that sea level continues to rise due to the expansion and mixing of water in warming oceans.

Although our results are based on a climate model, they fall within the range of others’ projections and help reveal the potential magnitude of climate disruption over longer time scales.

To truly describe what a low attenuation / high heat world could look like compared to what we’ve experienced so far, we used our projections and diverse research expertise to illuminate a series of nine paintings spanning a thousand years ( 1500, 2020, and 2500 CE) in three major regional landscapes (the Amazon, the Midwestern United States, and the Indian subcontinent). Images from the year 2500 are centered on RCP6.0 projections and include slightly advanced but recognizable versions of today’s technologies.

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 temperatures. global. If we fail to stop global warming, the next 500 years and beyond will change the Earth in ways that challenge our ability to maintain many essentials for survival, especially in cultures historically and geographically. roots that give us meaning and identity.

The Earth in our high-end projections is alien to humans. The choice we face is to urgently reduce emissions, while continuing to adapt to the warming that we cannot escape from emissions so far, or to start envisioning life on an Earth very different from this one.

Climate projections for 2,500 show Earth foreign to humans

SourceClimate projections for 2,500 show Earth foreign to humans

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