Limiting global average temperature increase to "well below" 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit that increase to 1.5 degrees Celsius--as agreed at the United Nations Climate Change Conference in Paris last year--will do little to stop portions of the world from becoming uninhabitable.
That's according to a new study published in the journal Climatic Change, which compares data from 1986 to 2005 with predictions from 26 climate models over the same period to project climate conditions for two future periods--2046 to 2065 and 2081 to 2100. In both cases, the highest temperature rise is predicted in summer in the Middle East and North Africa. By 2050, both study projections find the global temperature will be close to or have exceeded the 2 degree Celsius target.
"We have been investigating environmental issues, especially airborne dust, air quality and climate change, in the Middle East for many years," said Jos Lelieveld of the Max Planck Institute for Chemistry and study co-author. "Recently, we 'expanded' our interest to include North Africa, and discovered the important role of desert warming amplification in summer. It is evident that this can affect human habitability in the entire region. Since the Middle East and North Africa are troubled by many unfortunate developments, exceedingly hot summers can be expected to exacerbate problems."
A separate study by the World Bank suggests that the Middle East, North Africa, and central and South Asia could suffer large economic hits due to water scarcity associated with climate change. These regions could see their growth rates decline by as much as 6 percent of GDP by 2050 due to water-related impacts on agriculture, health and incomes.
"When we look at any of the major impacts of climate change, they one way or another come through water," said Richard Damania, lead author of the report. "So it will be no exaggeration to claim that climate change is really in fact about hydrological change."
To mitigate the impact of climate change on water supplies, the report suggests better planning for water resource allocation, adoption of incentives to increase water efficiency and investments in infrastructure for more secure water supplies and availability.
As Ocean Temps Rise, Ocean Oxygen Decreases
According to a new study in the journal Global Biogeochemical Cycles, ocean oxygen levels are decreasing due to climate change--with grave consequences for oxygen-reliant sea life such as crabs, squids, and many kinds of fish. The authors say the deoxygenation effect is already detectable in the southern Indian Ocean and parts of the eastern tropical Pacific and the Atlantic.
"Loss of oxygen in the ocean is one of the serious side effects of a warming atmosphere, and a major threat to marine life," said lead author Matthew Long, a researcher at the National Center for Atmospheric Research (NCAR).
The study uses a climate change model to attempt to determine precisely when ocean "deoxygenation" can be attributed to human-induced climate change, suggesting that differentiating between climate change-related losses and natural fluctuations will become increasingly less difficult. It predicts that by the 2030s, climate-change-related oxygen losses will be pervasive and obvious if greenhouse gas emissions continue unchecked. By the year 2100, it says, a significant fraction of the world's oceans will experience some deoxygenation due to human activity.
"Since oxygen concentrations in the ocean naturally vary depending on variations in winds and temperature at the surface, it's been challenging to attribute any deoxygenation to climate change," Long said. "This new study tells us when we can expect the effect from climate change to overwhelm the natural variability."
As seas warm, their capacity to absorb oxygen at the surface decreases, along with water turnover, which in turn decreases the chances that oxygen at the surface will move under the surface. That's because as water heats, it expands and becomes lighter than the water beneath it and therefore less likely to sink. The low oxygen levels can create dead zones.
Florida Keys Coral Reefs Reach Climate-Related 'Tipping Point'
Two weeks after the world learned that 93 percent of Australia's Great Barrier Reef has been bleached comes word of damage to reefs around South Florida and the Keys as a result of ocean acidification linked to warming waters. According to research in the journal Global Biogeochemical Cycles, reefs in the upper Florida Keys may be losing more limestone than they create each year--a "tipping point" that was projected for 2050 (subscription).
"These bleaching events are an acute problem caused by hot weather spells," said study co-author Chris Langdon, a professor at the University of Miami's Rosenstiel School of Marine and Atmospheric Science. "Acidification is chronic; it lasts 365 days out of the year. This is one reason we have to reduce carbon dioxide emissions sooner than later."
Typically, conditions in the ocean, such as water temperature and light, are favorable for the growth of coral limestone in spring and summer and are less favorable in fall and winter. As oceans absorb atmospheric carbon dioxide and ocean pH decreases, the natural summer growth cycle of coral decreases such that the effects of coral dissolution from ocean acidification cannot be offset.
The study findings are based on water samples taken along the 124-mile stretch of the Florida Reef Tract north of Biscayne National Park to the Looe Key National Marine Sanctuary. Because the data were collected in 2009 and 2010, the researchers suggest that another analysis should be conducted.
"The worst bleaching years on record in the Florida Keys were 2014-2015, so there's a chance the reefs could be worse now," said Langdon.
The Climate Post offers a rundown of the week in climate and energy news. It is produced each Thursday by Duke University's Nicholas Institute for Environmental Policy Solutions.