Thursday, March 23, 2017

  Thursday, Mar 23

Global surface temperature relative to 1880-1920 based on GISTEMP analysis (mostly NOAA data sources, as described by Hansen, J., R. Ruedy, M. Sato, and K. Lo, 2010: Global surface temperature change. Rev. Geophys., 48, RG4004.  We suggest in an upcoming paper that the temperature in 1940-45 is exaggerated because of data inhomogeneity in WW II. Linear-fit to temperature since 1970 yields present temperature of 1.06°C, which is perhaps our best estimate of warming since the preindustrial period.

Eating Less Beef Dropped Americans' Carbon Emissions by 9%

A decline in carbon-intensive foods like beef and orange juice has shrunk individuals' carbon footprints between 2005 and 2014

Beef (Credit: Sean Gallup/Getty Images) Click to Enlarge.
The carbon footprint of the average American's diet has shrunk by about 9 percent, largely because people are eating less beef, according to a new report.

Changes in the American diet—lower consumption of not only beef, but orange juice, pork, whole milk and chicken—meant that the average American's diet-related greenhouse gas emissions dropped from 1,932 kilograms in 2005 to 1,762 in 2014.

The analysis "just shows that small changes in our diets have impacts," said Sujatha Bergen, a food specialist at the Natural Resources Defense Council.  "There's a very concrete association between reduced red meat consumption and reduced emissions."

The biggest contributor to the reduction was a decline in beef consumption of about 19 percent over the course of the decade, adding up to a cumulative reduction of 185 million tons of climate change pollution.  Total emissions cuts from dietary changes were 271 million tons. During that time, overall U.S. greenhouse gas emissions averaged more than 6 billion tons a year.

Despite the improvement, the dietary changes pale by comparison to overall American emissions from a wealthy lifestyle.  The average American has a carbon footprint of about 16 tons and the average U.S. car accounts for roughly 5 tons of emissions per year.  China is the world leader in total carbon pollution, but the average Chinese citizen is responsible for less than half that amount. 

Americans eat more beef per capita than any other country except Argentina and Uruguay, and beef still contributed more than a third of the United States' diet-related climate emissions — about 34 percent in 2014.

Read more at Eating Less Beef Dropped Americans' Carbon Emissions by 9%

Cost of U.S. Car Fuel Standards Could Be 40 Percent Lower

A woman pumps gas at a station in Falls Church, Virginia December 16, 2014. (Credit: Reuters/Kevin Lamarque) Click to Enlarge.
The cost to implement tough fuel-efficiency standards for cars imposed by the Obama administration for the first half of the next decade could be up to 40 percent lower than previously estimated using existing conventional technologies, according to a report from a nonprofit group released on Wednesday.

If accurate, the report could present a challenge to automakers which have lobbied strongly against the implementation of the standards largely on the grounds of excessive cost.

Technologies like turbo-chargers, advanced transmissions and use of lighter weight materials - such as aluminum instead of steel - could reduce compliance costs by 34 percent to 40 percent per vehicle from 2022 through 2025, according to the report by the International Council on Clean Transportation (ICCT), an independent research group.

"All of those evolutionary changes, just getting a few percent here and a few percent there from those allow more cost-effective implementation of the regulations, said the report's principal author Nic Lutsey.

Instead of an average cost of $875 per vehicle for incremental technology needed to meet the new standards, as compared with 2021 standards, estimated by the U.S. Environmental Protection Agency (EPA), the ICCT's analysis of available data is for an additional cost of $551.

Under former Democratic President Barack Obama the EPA and the National Highway Traffic Safety Administration, in cooperation with the California Air Resources Board (CARB), negotiated the rules with automakers in 2012.

They were aimed at doubling average fleet-wide fuel efficiency to 54.5 miles per gallon (mpg) by 2025, although the real-world mileage figures would be much lower - the ICCT report assumes 35 mpg in 2025 versus a fleet average of 26 mpg today.

Republican U.S. President Donald Trump, who took office in January, last week ordered a review of those standards which many in the industry expect will lead to a relaxation of the fuel-efficiency targets or a slowdown in their implementation.

Automakers, through their lobbying groups, have said the Obama rules were too expensive and could cost American jobs.

California is expected to press forward with the Obama administration rules at a CARB meeting being held this Thursday and Friday. 

Read more at Cost of U.S. Car Fuel Standards Could Be 40 Percent Lower:  Report

Global Warming Is Increasing Rainfall Rates

The world is warming because humans are emitting heat-trapping greenhouse gases.  We know this for certain; the science on this question is settled.  Humans emit greenhouse gases, those gases should warm the planet, and we know the planet is warming.  All of those statements are settled science.

Okay so what?  Well, we would like to know what the implications are.  Should we do something about it or not?  How should we respond?  How fast will changes occur?  What are the costs of action compared to inaction?  These are all areas of active research.

Part of answering these questions requires knowing how weather will change as the Earth warms.  One weather phenomenon that directly affects humans is the pattern, amount, and intensity of rainfall and the availability of water.  Water is essential wherever humans live, for agriculture, drinking, industry, etc.  Too little water and drought increases risk of wild fires and can debilitate societies.  Too much water and flooding can occur, washing away infrastructure and lives.

It’s a well-known scientific principle that warmer air holds more water vapor.  In fact the amount of moisture that can be held in air grows very rapidly as temperatures increase.  So, it’s expected that in general, air will get moister as the Earth warms – provided there is a moisture source.  This may cause more intense rainfalls and snow events, which lead to increased risk of flooding. 

But warmer air can also more quickly evaporate water from surfaces.  This means that areas where it’s not precipitating dry out more quickly.  In fact, it’s likely that some regions will experience both more drought and more flooding in the future (just not at the same time!).  The dry spells are longer and with faster evaporation causing dryness in soils.  But, when the rains fall, they come in heavy downpours potentially leading to more floods.  The recent flooding in California – which followed a very intense and prolonged drought – provides a great example.

Okay so what have we observed?  It turns out our expectations were correct.  Observations reveal more intense rainfalls and flooding in some areas.  But in other regions there’s more evaporation and drying with increased drought.  Some areas experience both.

Some questions remain.  When temperatures get too high, there’s no continued increase in intense rain events.  In fact, heavy precipitation events decrease at the highest temperatures. There are some clear reasons for this but for brevity, regardless of where measurements are made on Earth, there appears to be an increase of precipitation with temperature up until a peak and thereafter, more warming coincides with decreased precipitation. 

A new clever study by Dr. Guiling Wang from the University of Connecticut and her colleagues has looked into this and they’ve made a surprising discovery.  Their work was just published in Nature Climate Change.  They report that the peak temperature (the temperature where maximum precipitation occurs) is not fixed in space or time.  It is increasing in a warming world. 

The idea is shown in the sketch below.  Details vary with location but, as the world warms, there is a shift from one curve to the next, from left to right.  The result is a shift such that more intense precipitation occurs at higher temperatures in future, while the drop-off moves to even higher temperatures.

Read more at Global Warming Is Increasing Rainfall Rates

Climate Change Could Lead to an Uptick in Type-2 Diabetes

Yet another way global warming poses a risk to health.

The association between mean annual temperature and diabetes incidence in the United States over the period 1996–2009. (Credit: BMJ) Click to Enlarge.
Global warming already widens the footprint of Lyme disease while Zika virus exacerbates asthma and lung diseases and increases the risks posed by violent weather and wildfires.

Now, new research suggests rising temperatures lead to a surge in diagnoses of type-2 diabetes.

The study, published Monday in the BMJ Open Diabetes Research & Care, compared annual average temperatures across the United States from 1996 to 2009 with reported new cases of type-2 diabetes.  The disease, which typically develops later in life, prevents the body from absorbing glucose needed to produce energy.  In particularly hot years, the number of new diagnoses spiked.

“When it gets warmer, there is higher incidence of diabetes,” Lisanne Blauw, the study’s co-author and a PhD candidate at the Netherlands-based Einthoven Laboratory, told The Huffington Post by phone on Tuesday.  “It’s important to realize global warming has further effects on our health, not only on the climate.”

Read more at Climate Change Could Lead to an Uptick in Type-2 Diabetes

The Foundation of Aquatic Life Can Rapidly Adapt to Global Warming, New Research Suggests

Phytoplankton can increase the rate at which they take in carbon dioxide and release oxygen while in warmer water temperatures. (Credit: Click to Enlarge.
Important microscopic creatures which produce half of the oxygen in the atmosphere can rapidly adapt to global warming, new research suggests.

Phytoplankton, which also act as an essential food supply for fish, can increase the rate at which they take in carbon dioxide and release oxygen while in warmer water temperatures, a long-running experiment shows.

Monitoring of one species, a green algae, Chlamydomonas reinhardtii, after ten years of them being in waters of a higher temperature shows they quickly adapt so they are still able to photosynthesise more than they respire.

Phytoplankton use chlorophyll to capture sunlight, and photosynthesis to turn it into chemical energy.  This means they are critical for reducing carbon dioxide in the atmosphere and for providing food for aquatic life.

It is crucial to know how these tiny organisms - which are not visible to the naked eye - react to climate change in the long-term.  Experts had made predictions that that climate change would have negative effects on phytoplankton.  But a new study shows green algae can adjust to warmer water temperatures.  They become more competitive and increase the amount they are able to photosynthesize.

Read more at The Foundation of Aquatic Life Can Rapidly Adapt to Global Warming, New Research Suggests