2021 Global Change Outlook - Long-Term Climate Stabilization Goals

The 2021 Global Change Outlook presents the MIT Joint Program’s latest projections for the future of the Earth’s energy, managed resources (including water, agriculture and land), and climate, as well as prospects for achieving the Paris Agreement’s short-term targets (as defined by Nationally Determined Contributions, or NDCs) and long-term goals of keeping the increase in the average global temperature below 2°C or even 1.5°C.

2021 Global Change Outlook

The massive impact of the Covid-19 pandemic on lives and economies underscores that our collective survival and well-being hinges on our willingness to confront environmental threats that have global consequences. Key to protecting lives and making communities more resilient to such threats will be an emphasis on proactive, science-based decision-making at all levels of society. And among the most serious risks that science can help illuminate and alleviate are those resulting from human-induced climate change.

To minimize those risks, the Paris Agreement(Global Change Outlook)aims to commit nearly 200 nations to implement greenhouse gas emissions-reduction policies consistent with keeping the increase in the global average temperature since preindustrial times to well below 2 degrees Celsius — and pursue efforts to further limit that increase to 1.5 C. Recognizing that the first set of submitted near-term Paris pledges, known as Nationally Determined Contributions (NDCs), are inadequate by themselves to put the globe on track to meet those long-term targets and thus avoid the worst consequences of climate change, the accord calls for participating nations to strengthen their NDCs over time. To that end, the United States and a few other nations announced more stringent emissions-reduction goals for 2030 at the virtual climate summit convened by President Joe Biden in April.  

To support decision-makers now engaged in or impacted by this ongoing, international effort to stabilize the climate, the MIT Joint Program on the Science and Policy of Global Change has released its 2021 Global Change Outlook. Based on a rigorous, integrated analysis of population and economic growth, technological change, NDCs, Covid-19 impacts, and other factors, the report presents the Joint Program’s latest projections for the future of the Earth’s energy, food, water and climate systems, as well as prospects for achieving the Paris Agreement’s short and long-term climate goals.

Global Change Outlook Projections are provided for a baseline “Paris Forever” scenario, in which current (as of March 2021) NDCs are maintained in perpetuity; a Paris 2 C scenario that caps global warming at 2 C by 2100; and two scenarios — “Accelerated Actions” (which includes the newly announced U.S. goal for 2030) and Paris 1.5 C — which limit warming to 1.5 C by 2100. Uncertainty is quantified using 400-member ensembles of projections for each scenario. This year’s outlook introduces a visualization tool that enables a higher-resolution exploration of the first three scenarios.

Energy

  • Global primary energy use in the Paris Forever scenario grows to about 770 exajoules (EJ) by 2050, up by 31% from about 590 EJ in 2020. The share of fossil fuels drops from the current 80% to 70% in 2050. All energy types except coal grow from 2020 to 2050, led by non-biomass renewable energy (wind and solar) with more than a 5.6-fold increase. Natural gas consumption increases by about 50%, hydropower grows by 28% and oil use by 14%. Both nuclear and bioenergy increase by about 3%, while global coal consumption decreases by 7%. Coal’s share of primary energy declines from about 26% in 2020 to 18% in 2050.
  • The Paris Agreement pledges made by countries for the year 2030 do not substantially decrease the share of fossil fuels in global primary energy use. From about 80% in 2019, it declines to 74% in 2030. After 2030 it continues to decline, but even by 2050, a majority of global energy comes from fossil fuels in both Paris Forever and Paris 2°C scenarios. From 2020 to 2050, Covid-19 impacts on energy use and renewable energy deployment are relatively modest (2–4% reduction in energy use each year and virtually the same pathway for renewables relative to the non-Covid trajectory).

 

Private Vehicles and Transportation

  • From about 10 million electric vehicles (EVs) in 2020, EV stock in the Paris Forever scenario reaches 100 million EVs in 2030, almost 300 million in 2040 and nearly 650 million in 2050. With the light-duty vehicle (LDV) stock increasing overall from 1.1 billion in 2020 to about 1.7 billion in 2050, the EV share of the LDV fleet reaches 38% in 2050. EV growth is even faster in the Paris 2°C scenario, with a projected 825 million EVs on the road by 2050, comprising 50% of the LDV fleet.

 

Electricity Production

  • In the Paris Forever scenario, global electricity production (and use) grows by 67% from 2020 to 2050. In comparison to primary energy growth of 31% over the same period, electricity grows twice as fast, resulting in a continuing electrification of the global economy. Generation from variable renewables exhibit the fastest growth, with a 6-fold increase between 2020 and 2050.
  • In the Paris 2°C scenario, global electricity production grows even faster, rising by 69% between 2020 and 2050. Policies after 2030 lead to a larger growth in variable renewables, which increase 9.7 times from 2020 to 205

Energy Prices

  • In the Paris Forever scenario, the oil price increases by 15% from 2020 to 2050, reaching $67/barrel. In the Paris 2°C scenario, this upward trend is reversed by a decrease in oil demand after 2030. The oil price rises to $64/barrel by 2030 and then declines to $45/barrel in 2050. Natural gas prices vary by region—rising with increased demand for replacing coal-based power generation, falling when renewables expand significantly. Coal prices also vary by region: prices decline in most regions due to reductions in demand for coal, with China a notable exception.
  • The average global electricity price increases from 2020 to 2050 by 16% in the Paris Forever scenario and by 26% in the Paris 2°C scenario. Price increases are mostly driven by policy requirements to include more low-carbon generation options.

 

Emissions and Climate

 

Emissions

  • Covid-19 impacts on global GHG emissions persist but diminish over time—a 2% reduction by 2025 and about 1% in 2030–2040 below what they would be in a non-Covid world. After that, the difference imposed by the pandemic is less than 1%.
  • Global GHG emissions in the Paris Forever scenario initially decrease from about 48 gigatonnes of CO2-equivalent (Gt CO2e) in 2020 to about 47.5 Gt CO2e in 2030, and then gradually increase to about 51 Gt CO2e in 2050 due to growth in countries with less stringent emissions targets. In the Paris 2°C scenario, GHG emissions follow the same path as in Paris Forever until 2030, and then more aggressive policies reduce them to 34 Gt CO2e by 2050. In the Accelerated Actions scenario, global GHG emissions decline to 20 Gt CO2e by 2050. Collectively, the world reduces its GHG emissions by almost 60% in 2050 relative to 2020 in that case.

 Climate

  • Carbon dioxide (CO2) concentrations in the Paris Forever scenario continue to rise throughout (and after) the 21st century. By the beginning of the 2040s, the entirety of the Integrated Global System Modeling (IGSM) framework ensemble projection rises above 450 ppm of global CO2 concentrations. In addition, by mid-22nd century, more than half of the IGSM ensemble runs (i.e., at least 50% probability) show CO2 concentration at double their current level. Also by that time, we project with 100% likelihood that CO2e concentrations will rise to at least double the current level.
  • By 2065, more than half of the IGSM ensemble’s Paris Forever projections exceed 2°C global climate warming, a fraction that rises to more than 75% by 2071 and more than 95% by 2085. By 2100, 95% of the IGSM projections indicate a global climate warming of at least 2.25°C, and the central tendency (i.e., median) of the projected warming is 2.8°C. All of the ensemble’s warming projections exceed 1.5°C warming after 2055. By mid-22nd century, the IGSM projections show that the world experiences at least a 3.3°C warming (in 95% of the IGSM ensemble runs) and most likely a warming of 4.1°C (median result).
  • The MIT Earth System Model’s (MESM’s) global hydrologic sensitivity ranges from 1.7–3.3% per °C. In the Paris Forever ensemble, the MESM’s projected increase in global precipitation between today and mid‑century is projected to most likely (i.e., median result) be 0.04 mm/day, approximately an additional 7,400 km3 (or nearly 2 quadrillion gallons) of water that will be delivered from the atmosphere each year, which exceeds the current estimate of global annual human water consumption (4,600 km3). By 2100, the total change in precipitation will most likely rise to 0.11 mm/day (or 21,200 km3/yr)—nearly triple that of the mid‑century change.
  • In both the Paris 2°C and Paris 1.5°C scenarios, global temperature will continue to rise through the next two decades. By mid‑century, the Paris 1.5°C scenario’s global temperature will stabilize, while the Paris 2°C global temperature will continue to rise through the 2070s. The Paris 2°C scenario also indicates that even among all the plausible outcomes captured by the IGSM ensemble, there is no likelihood of even the “coolest” trajectories to remain below 1.5°C at the end of the century. On the other hand, the Paris 1.5°C ensemble scenario can virtually assure the world of remaining below 2°C of global-averaged warming.
  • The Paris 2°C and Paris 1.5°C scenarios not only stabilize global precipitation increase (by 2060 in Paris 1.5°C, and by 2100 in Paris 2°C), but substantially reduce the magnitude and potential range of increases. Paris 2°C cuts the increases in half and Paris 1.5°C reduces them to almost a third of the Paris Forever global precipitation changes. The hydrologic sensitivity of total precipitation from heavy and extreme precipitation events can be 5–10 times that of global mean precipitation. Thus, any global increase in precipitation conveys amplified risk of flooding worldwide. Therefore, these aggressive mitigation scenarios convey considerable reduction in both flood risk and uncertainty in the proportion (and cost) of adaptive actions that would otherwise be required.

 

Managed Resources

 

Water

  • Under the Paris Forever scenario by mid‑century, approximately 5.8 billion people worldwide will be exposed to shortfalls in water supply (societal stress) across the major river basins where they reside. In addition, 3.6 billion people will be living within basins exposed to environmental water stress, and 3.2 billion people will be exposed to both societal and environmental water-stressed conditions.
  • With a global population projected to reach 9.7 billion by 2050, the Paris Forever scenario indicates that more than half of the world’s population will experience pressures to its water supply, and that 3 of every 10 people will live in basins experiencing compounding societal and environmental pressures on water resources.

Agriculture

  • Under the Paris Forever scenario, overall food production increases by 90% from 2020 to 2050, crop production by 70% and livestock production by 81%. Livestock production grows faster than crop production due to higher shares of protein-rich food in diets when income rises. Food production grows faster than livestock and crop production.
  • Under the Paris Forever scenario, technological change and changing agricultural management practices result in greater yields, which prevent high increases in prices. By 2050 food prices are only 2% higher than in 2020. Crop prices rise a bit more (7%), while livestock prices rise by 42% and forest products by 33%.
  • Under the Paris 2°C scenario, the value of crop output is 1.5% lower than in the Paris Forever scenario, while livestock output reduces by 1.9% and food output by 2.3%.Prices of livestock products initially increase, declining later by 4% by 2050 compared to the Paris Forever scenario, while prices of food products and crop products decrease by 5.4% and 2.8% respectively.

 

Land-Use Change

  • Global land-use projections from 2020 to 2050 are quite stable. Natural forest areas decrease by 1% and natural grasslands by 3%. These are converted mostly to cropland areas, which increase by 7%, while pasture lands increase by only 0.14%.
  • Land-use changes in the Paris 2°C scenario are similar to those in the Paris Forever scenario by 2050, but quite different by 2100. By that time, the area dedicated to bioenergy output reaches 17% of total cropland area, while it is only 6% in the Paris Forever scenario. Cropland area increases by 22%, while pastureland decreases by 31% to give room for cropland and bioenergy expansion.

 

Stabilizing Climate in the Long-Term 

2021 Global Change Outlook,The Paris Agreement established more precise long-term temperature targets than previous climate pacts by specifying the need to keep “aggregate emissions pathways consistent with holding the increase in global average temperature well below 2°C above pre-industrial levels” and further adding the goal of “pursuing efforts to limit the temperature increase to 1.5°C.”

Our outlook shows that we could dramatically reduce overall climate risk through more ambitious and accelerated policy measures and investments aligned with meeting the Paris Agreement’s long-term 1.5 C or 2 C climate targets,” says MIT Joint Program Director of Global Change Outlook, Ronald Prinn. “Decision-makers in government, industry, and financial institutions can play a key role in moving us further along this path.

 

Source: Scitechdaily,Globalchange.mit,

Full Document(PDF): 2021 Global Change Outloo

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