Earth Systems

On January 12, 2022, MIT Joint Program Research Scientist Kenneth Strzepek presented a talk entitled "The role of Nile water resources in the economic development of Egypt and Ethiopia, and the potential impacts of the GERD filling policies." The talk was part of "The Nile River Basin in Crisis: Water Sharing and Transboundary Conflict or Cooperation" Webinar Series, presented by the UCLA African Studies Center. 

Oultine:

The role of Nile water resources in the economic development of Egypt and Ethiopia, and the potential impacts of the GERD filling policies
Testing the skill of a species distribution model using a 21st century virtual ecosystem

Authors' Summary: Marine plankton communities play a central role within Earth's climate system, with important processes often divided among different “functional groups.” Changes in the relative abundance of these groups can therefore impact on ecosystem function. However, the oceans are vast, and samples are sparse, so global distributions are not well known. Statistical species distribution models (SDM's) have been developed that predict global distributions based on their relationships with observed environmental variables. They appear to perform well at summarizing present day distributions, and are increasingly being used to predict ecosystem changes throughout the 21st century. But it is not guaranteed that such models remain valid over time.

Rather than wait 100 years to find out, we applied a statistical SDM to a complex virtual ocean, and trained it using virtual observations that match real-world ocean samples. This allows us to jump forward to the end-of-century to test the accuracy of our predictions. The SDM performed well at qualitatively predicting “present day” plankton distributions but yielded poor end-of-century predictions. Our case study emphasizes both the importance of environmental variable selection, and of changes in the underlying relationships between environmental variables and plankton distributions, in terms of model validity over time.

Future energy: In search of a scenario reflecting current and future pressures and trends

Abstract: Growing societal pressures, technological trends and government and industry actions are moving the world toward decarbonization and away from “business-as-usual.” As such, the concept of a single/obvious “business as usual” or “reference” scenario is no longer relevant. Instead, there are multiple plausible futures that should be explored. We contribute one such scenario that carefully considers emissions-reduction trends and actions that are likely in the future, absent a globally coordinated mitigation effort. We explore the long-term implications for energy, emissions and temperature outcomes if the world continues to address climate change in the way it has so far—through piecemeal actions and growing social and technological pressures.

This Growing Pressures scenario results in a central scenario outcome of about 3°C of surface temperature warming, which is higher than the “well below 2°C” level aspired to by the Paris Agreement, but lower than many widely used “no-policy” scenarios. Ongoing and growing pressures of change, the roots of which are clearly visible today, could deliver a plausible energy transition scenario to near-zero emissions that plays out over the coming century.

While a more aggressive transition is clearly required, this finding highlights the need to bring actions forward in time to achieve an improved outcome making use of clearly identifiable policies and technologies.

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