Washington/London (ISJ) - Even if humans could instantly turn off all emissions of greenhouse gases, Earth would continue to heat up about two more degrees Fahrenheit by the turn of the century, according to a sophisticated new analysis published in the latest issue of journal Nature Climate Change.
If current emission rates continue for 15 years, the research shows, odds are good that the planet will see nearly three degrees Fahrenheit (1.5 Celsius) of warming by then.
"This 'committed warming' is critical to understand because it can tell us and policymakers how long we have, at current emission rates, before the planet will warm to certain thresholds," said Robert Pincus, a scientist with the Cooperative Institute for Research in Environmental Sciences (CIRES), a partnership of the University of Colorado Boulder and NOAA. "The window of opportunity on a 1.5-degree [C] target is closing."
During United Nations meetings in Paris last year, 195 countries including the United States signed an agreement to keep global temperature rise less than 3.5 degrees F (2 C) above pre-industrial levels, and pursue efforts that would limit it further, to less than 3 degrees Fahrenheit (1.5 C) by 2100.
The new assessment, co-authored by Pincus and Thorsten Mauritsen of the Max Planck Institute for Meteorology, is unique in that it does not rely on computer model simulations, but rather on observations of the climate system to calculate Earth's climate commitment. Their work accounts for the capacity of oceans to absorb carbon, detailed data on the planet's energy imbalance, the climate-relevant behaviour of fine particles in the atmosphere and other factors.
"Our estimates are based on things that have already happened, things we can observe, and they point to the part of future warming that is already committed to by past emissions," said Mauritsen. "Future carbon dioxide emissions will then add extra warming on top of that commitment."
Unrelated to the study by Pincus and Mauritsen, a global ranking of impacts of climate change over the next 30 years shows, India is amongst the 16 countries at 'extreme risk' of global warming. Bangladesh (1), India (2), Philippines (6), Vietnam (13) and Pakistan (16) are in the highest risk category.
The latest Climate Change Vulnerability Index, CCVI released by global risks advisory firm Maplecroft, has evaluated 42 social, economic, environmental factors to assess national vulnerabilities across three core areas. These include exposure to climate-related natural disasters and sea-level rise, human sensitivity in terms of population patterns, development, natural resources, agricultural dependency and conflicts, and thirdly, the adaptive capacity of a country's government and infrastructure to combat climate change.
Sources: University of Colorado Boulder/ Maplecroft
Image courtesy: University of Colorado Boulder
Link to the study: http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3357.html
Link to Maplecroft Report: https://maplecroft.com/about/news/ccvi.html