Everglades (and south Florida, including Miami) with 5ft of sea level rise
The Florida Everglades, where elevation above sea level is often measured in single digits, is on of the most susceptible areas of the country to sea level rise. In addition to its low coastal elevation, the Everglades are threatened as a result of a history of wetland degradation that changed the way water flowed through the large wetland system. Restoring natural freshwater flows will help protect the everglades from the intrusion of salt water due to sea level rise, but it must be done quickly.
Dr. Harold Wanless of the University of Miami Department of Geological Sciences created a series of maps showing the Everglades under varying scenarios of sea level rise. This is the Everglades in 1995.
While deforestation is a major source of global carbon emissions (see previous two posts), the expansion of agriculture into drained organic soils also releases carbon. Wetlands, and especially peatlands, have waterlogged soils. As a result, their soils are depleted of oxygen, preventing decomposition. This means that the carbon in plants and animals is stored in the soils. When these soils are drained, the oxygen returns and organic material decomposes. Decompostion releases the carbon stored in that material. Thus, draining wetland soils releases carbon dioxide and contributes to climate change.
FAO adds emissions from cropland expansion into drained organic soils to deforestation. The result: significant increases in carbon emissions from Indonesia, which has substantial peatlands.
The figures from the previous post on deforestation (from the UN Food and Agriculture Organization) have a significant impact on carbon emissions and climate change. Because deforestation releases carbon stored in plants and soils, deforestation has become a major source of global carbon dioxide emissions. Countries with greater deforestation have greater emissions as a result.
Forest conversion in Brazil 1990-2010 released 25.8 billion metric tons of CO2. The next four greatest emitters from deforestation were Indonesia, Nigeria, the Democratic Republic of the Congo and Venezuela. Combating climate change will require reigning in deforestation.
This graph shows net forest conversion (deforestation that replaces forest with a new land use) from 1990-2010. Brazil and Indonesia stand out as the hot spots of deforestation.
In contrast, China, the United States and Vietnam experienced afforestation and reforestation.
California’s climate change law (AB 32), which puts a price on carbon emissions and creates a cap-and-trade system to reduce greenhouse gas emissions, is yielding substantial reductions in emissions from oil refineries. These refineries are a major source of carbon emissions, along with a host of other toxic chemicals like ammonia, lead, benzene, mercury and acid gases.
Data from the California Air Resources Board shows that 11 refineries substantially reduced emissions between 2010 and 2011, in addition to cuts in the release of other toxic pollutants. Evidence shows that these reductions not a result of cuts in production, but to refineries investing in and upgrading equipment in response to AB 32. An example is Valero’s refinery in Benicia, CA, which decreased covered emissions by over 95,000 metric tons, while also cutting ammonia emissions by 98%, sulfuric acid by 84%, and benzene by 49%, through the installation of a new flue gas scrubber.
(continued from previous post)
The big story in Houser and Mohan’s study is where these cleaner forms of energy are coming from that are responsible for half of the drop in emissions. It’s generally assumed that the drop is a result of cleaner and cheap natural gas pushing out dirty coal. However, Houser and Mohan show that we shouldn’t be counting out reneables.
Plumer:
Natural gas is indeed pushing out dirtier coal, and that makes a sizable difference (burning natural gas for electricity emits about half the carbon-dioxide that burning coal does). But wind farms are also sprouting up across the country, thanks to government subsidies. What’s more, industrial sites are burning more biomass for heat and electricity, while biofuels like ethanol are nudging out oil. All of that has done a lot to cut emissions.
Brad Plumer in the Washington Post explains a new study on the dramatic drop in carbon emissions in the U.S. over the past five years. This graph shows a hypothetical level of emissions that were projected based on trends from 1990-2005, compared to the actual level of emissions in 2012. It then breaks down the causes.
Plumer explains:
The recession and financial crisis, obviously, made a big difference. A weaker economy has meant less demand for energy — that was responsible for more than half the drop compared with business as usual.
Meanwhile, Houser and Mohan find the U.S. economy actually hasn’t become vastly less energy-intensive over time (the blue bar). Yes, overall efficiency has gone up — Americans are buying more fuel-efficient cars and trucks, etc. But the country is also no longer shedding manufacturing jobs as quickly as it was during the 1990s. So the amount of energy we use per unit of GDP has generally followed historical trends, improving only gradually.
The real change has come in the type of energy that the United States is using. The country is now relying more heavily cleaner forms of energy than it used to, and that explains about half of the fall in emissions
