Sea level rise poses one of the biggest threats to human systems in a globally warming world, potentially causing trillions of dollars' worth of damages to flooded cities around the world. As surface temperatures rise, ice sheets are melting at record rates and sea levels are rising.

But there may be some good news amid the worry. Sea levels may not rise as high as assumed.

The collective climate targets submitted by Governments to the UN will lead to global emissions far above the levels needed to hold warming to below 2°C, researchers at the Climate Action Tracker warned today.

The analysis by the consortium of four research organisations was released today in Bonn where Governments are meeting for the second to last week of negotiations ahead of the Paris summit on climate action.
 

Since the 1990s, scientists and policymakers have proposed limiting Earth’s average global surface temperature to 2 degrees C above pre-industrial levels, thereby averting the most serious effects of global warming, such as severe droughts and coastal flooding. But until recently, they lacked a comprehensive estimate of the likely social and economic benefits — from lives saved to economies preserved — that would result from greenhouse gas emissions reduction policies designed to achieve the 2 C goal.

Now, a team of researchers from the MIT Joint Program on the Science and Policy of Global Change has published a study in Climatic Change that provides scenarios that climate scientists can use to estimate such benefits. The study projects greenhouse gas emissions levels and changes in precipitation, ocean acidity, sea level rise and other climate impacts throughout the 21st century resulting from different global greenhouse gas (GHG) mitigation scenarios. The scenarios include a business-as-usual future and one aimed at achieving significant GHG emission reductions limiting global warming since pre-industrial times to 2 C. Research groups convened by the U.S. Environmental Protection Agency have already begun using the MIT projections to evaluate the benefits of a 2 C emissions reduction scenario for agriculture, water, health, and other global concerns.

The economic ramifications of continuing the 20th century’s economic model, where unsustainable extraction and pollution conveys competitive advantage, are coming into sharp focus. Citigroup now projects a staggering $72 trillion global cost tied to man-made climate change during the 21st century. 

As a raindrop falls through the atmosphere, it can attract tens to hundreds of tiny aerosol particles to its surface before hitting the ground. The process by which droplets and aerosols attract is coagulation, a natural phenomenon that can act to clear the air of pollutants like soot, sulfates, and organic particles. Atmospheric chemists at MIT have now determined just how effective rain is in cleaning the atmosphere. 

A new international study is the first to use a high-resolution, large-scale computer model to estimate how much ice the West Antarctic Ice Sheet could lose over the next couple of centuries, and how much that could add to sea-level rise. The results paint a clearer picture of West Antarctica’s future than was previously possible. The study has been published in The Cryosphere, an open access journal of the European Geosciences Union (EGU).

“The IPCC’s [Intergovernmental Panel on Climate Change] 4th and 5th Assessment Reports both note that the acceleration of West Antarctic ice streams in response to ocean warming could result in a major contribution to sea-level rise, but that models were unable to satisfactorily quantify that response,” says Stephen Cornford, a research assistant at the University of Bristol, UK and lead-author of the study.

Each spring, powerful dust storms in the deserts of Mongolia and northern China send thick clouds of particles into the atmosphere. Eastward winds sweep these particles as far as the Pacific, where dust ultimately settles in the open ocean. This desert dust contains, among other minerals, iron — an essential nutrient for hundreds of species of phytoplankton that make up the ocean’s food base.

Global sea levels have risen nearly 3 inches in less than 25 years, with some locations around the world rising more than 9 inches, according to NASA’s latest satellite data. An intensive research effort now underway, aided by NASA observations and analysis, points to an unavoidable rise of several feet in the future.

At the end of November, governments will come together in Paris to hammer out agreements for a successor to the Kyoto Protocol. Under the KP, there are two greenhouse gas (GHG) emissions offsetting mechanisms: joint implementation (JI) and the Clean Development Mechanism (CDM).

JI allows countries with emissions-reduction commitments under the Kyoto Protocol to generate Emission Reduction Units (ERUs) from GHG reduction projects and transfer them to other countries. Almost 872 million ERUs had been issued under JI as of March 2015, about a third of all Kyoto offset credits. In a nutshell, JIs are carbon credits and include things like reforestation projects.

In addition to melting icecaps and imperiled wildlife, a significant concern among scientists is that higher Arctic temperatures brought about by climate change could result in the release of massive amounts of carbon locked in the region’s frozen soil in the form of carbon dioxide and methane. However, new research led by Princeton University researchers and published in The ISME Journal in August suggests that, thanks to methane-hungry bacteria, the majority of Arctic soil might actually be able to absorb methane from the atmosphere rather than release it.