Researchers from the Arctic Research Programme, managed at British Antarctic Survey, have shown for the first time that phytoplankton (plant life) in remote ocean regions can contribute to rare airborne particles that trigger ice formation in clouds.

Results published today in the journal Nature show that the organic waste from life in the oceans, which is ejected into the atmosphere along with sea spray from breaking waves, stimulates cloud droplets to freeze into ice particles. This affects how clouds behave and influence global climate, which is important for improved projections of future climate change.

Like the leaves of New England maples, phytoplankton, the microalgae at the base of most oceanic food webs, photosynthesize when exposed to sunlight. In the process, they absorb carbon dioxide from the atmosphere, converting it to carbohydrates and oxygen. Many phytoplankton species also release dimethyl sulfide (DMS) into the atmosphere, where it forms sulfate aerosols, which can directly reflect sunlight or increase cloud cover and reflectivity, resulting in a cooling effect. The ability of phytoplankton to draw planet-warming carbon dioxide (CO2) from the atmosphere and produce aerosols that promote further cooling has made ocean fertilization — through massive dispersal of iron sulfite and other nutrients that stimulate phytoplankton growth — an attractive geoengineering method to reduce global warming.

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.