What choices does the world have to make to keep global warming below 2C? | MIT News

When the 2015 Paris Agreement set a long-term goal of keeping global warming “well below 2 degrees Celsius, compared to pre-industrial levels” to avoid the worst impacts of climate change, he did not specify how his nearly 200 signatory countries could collectively reach this goal. Each nation has been left to its own devices to reduce greenhouse gas emissions in accordance with the 2C target. Now, a new modeling strategy developed at MIT Joint Program in the Science and Politics of Global Change which explores hundreds of potential future development paths provides new insights into the energy and technology choices needed for the world to reach this goal.

Described in a study appeared in the magazine Earth’s future, the new strategy combines two well-known computer modeling techniques to determine the energy and technology choices needed over the next few decades to reduce emissions enough to meet the Paris target.

The first technique, Monte Carlo analysis, quantifies levels of uncertainty for dozens of energy and economic indicators, including the availability of fossil fuels, the costs of advanced energy technologies, and population and economic growth; feeds this information into a multi-region, multi-economic sector model of the global economy that captures the intersectoral impacts of energy transitions; and runs this model hundreds of times to estimate the probability of different outcomes. The MIT study focuses on projections to 2100 of economic growth and emissions for different sectors of the global economy, as well as energy and technology use.

The second technique, scenario discovery, uses machine learning tools to filter databases of model simulations to identify outcomes of interest and their conditions of occurrence. The MIT study applies these tools in a unique way by combining them with Monte Carlo analysis to explore how different outcomes relate to each other (for example, do low-emissions outcomes necessarily imply large shares renewable electricity?). This approach can also identify individual scenarios, among the hundreds explored, that lead to specific combinations of outcomes of interest (e.g., scenarios with low emissions, high GDP growth, and limited impact on oil prices). ‘electricity), and also provide an overview of the conditions necessary for this combination of results.

Using this unique approach, researchers in the MIT Joint Program find several possible models for energy and technology development within a specified long-term climate goal or economic outcome.

“This approach shows that there are many paths to a successful energy transition that can be win-wins for the environment and the economy,” says jennifer morris, an MIT Joint Program Research Scientist and the study’s lead author. “To that end, it can be used to guide decision makers in government and industry to make wise energy and technology choices and to avoid biases in perceptions of what ‘must’ happen to achieve certain results.

For example, while achieving the 2C target, the global level of combined wind and solar power generation by 2050 could be less than three times or more than 12 times the current level (which is just over 2,000 terawatt hours). These are very different energy pathways, but both can be compatible with the 2C goal. Likewise, there are many different energy mixes that can be compatible with sustaining high GDP growth in the United States. while meeting the 2C objective, with different possible roles for renewables, natural gas, carbon capture and storage and bioenergy. The study finds that renewables are the most robust power investment option, with significant growth predicted for each of the long-term temperature goals explored.

The researchers also find that long-term climate goals have little impact on economic output for most economic sectors through 2050, but require each sector to significantly accelerate the reduction of its greenhouse gas emissions intensity. emissions (emissions per unit of economic output) to near-zero levels by mid-century.

“Given the range of development paths that may be compatible with achieving a 2 degree Celsius goal, policies that only target specific sectors or technologies may unnecessarily narrow the solution space, resulting in higher costs,” says the former joint program co-director at MIT. John Reilly, co-author of the study. “Our results suggest that policies designed to encourage a portfolio of technology and sector stocks can be a sound strategy that protects against risk.”

The research was funded by the Office of Science of the US Department of Energy.

Teresa H. Sadler