Dump fossil fuels for the health of our hearts

Air quality in London on April 3, 2014 fell to a level where it became hard to see normally-visible skyscrapers. Conditions hit a 9/10 risk ranking  thanks to a combination of pollution and dust blown in from the Sahara desert. Tackling such pollution could immediately improve people's health, stresses New York University's George Thurston. Image copyright David Holt, used via Flickr Creative Commons license.

Air quality in London on April 3, 2014 fell to a level where it became hard to see normally-visible skyscrapers. Conditions hit a 9/10 risk ranking thanks to a combination of pollution and dust blown in from the Sahara desert. Tackling such pollution could immediately improve people’s health, stresses New York University’s George Thurston. Image copyright David Holt, used via Flickr Creative Commons license.

Sometimes when I blow my nose and – inevitably – look into my handkerchief, I see that my snot is black. It doesn’t happen when I’m at home, in the small English city of Exeter, only when I’m in London. It’s a clear sign of the extra pollution I’m inhaling when I’m in the capital – one backed up by data published last week by Public Health England. Its striking report says that in 2010 73 deaths per thousand in the London borough of Waltham Forest, where my girlfriend’s sister lives, could be put down to grimy air. For Exeter, the figure was just 42 per 1000. Across the whole of England, pollution killed 25,002 people in 2010, or 56 of every 1000 deaths nationwide.

But wherever you live, air pollution will become even more important as the climate changes, while fighting this scourge could also help the world bring global warming under control. “There’s more than enough rationale for controlling emissions based on the health effects and the benefits that we get as a society from getting off of fossil fuels,” New York University’s George Thurston told me. “Those are the benefits that are going to accrue to the people who do the clean-up – locally and immediately, not fifty years from now.”

Public Health England is trying to draw attention to ‘particulate matter’, or dust, less than 2.5 micrometres in diameter, too small to see with our naked eye. You won’t find this ‘PM2.5’ pollution listed as people’s cause of death – it’s likely to be down as a heart attack or lung cancer. George has run huge studies in the US to help work out exactly how much such dust worsens people’s health. One study for the American Cancer Society followed 1.2 million men and women originally enrolled in 1982. Another, started in 1995, tracked over 500,000 US retirees over the following decade. And he was also a part of a worldwide project that last year showed ‘global particulate matter pollution is a major avoidable risk to the health of humankind’. Read the rest of this entry »

Advertisements

Climate change science anyone can play with

It’s all very well to read about climate change – but you can probably get a better understanding from actually exploring the data and underlying physics yourself. That’s been driven home by some recent comments on this blog by non-scientist readers wanting to do just this, or recommending that I do. Inspired by them, in this week’s blog entry I’m bringing together various different ways we can all do this. Don’t worry, I won’t tax any weary brain cells any more than they want to be. I’m organising the blog entry in order of increasing effort/difficulty – just bail out or take a break whenever you need to.

The volume occupied by the average yearly CO2 emitted by someone in the UK is as big as a building. Credit: Carbon Quilt

The volume occupied by the average yearly CO2 emitted by someone in the UK is as big as a building. Credit: Carbon Quilt

As a simple starter, try the Carbon Quilt tool that lets you see your CO2 emissions. If you click on this link or the image above you should first see the size of a ‘quilt’ or ‘patch’. That represents the average amount of CO2 people in your country emit, overlaid on a map. Try out the sphere and cube options, and the different options in the drop-down menu to see how big your carbon footprint really is.

Click here to see how hot the Earth's predicted to get in your lifetime, and the lifetimes of children born today. Credit: The Guardian

Click here to see how hot the Earth’s predicted to get in your lifetime, and the lifetimes of children born today. Credit: The Guardian

Another simple but powerful demonstration is the Guardian interactive guide to how warm it will get in our lifetimes pictured above.

Click here to see how unusual current CO2 levels are, and how much worse they're set to get. Credit: The Guardian

Click here to see how unusual current CO2 levels are, and how much worse they’re set to get. Credit: The Guardian

Still more powerful, I think, is this guide showing the significance of CO2 levels in the air hitting 400 parts per million last year. Read the rest of this entry »

Enhanced fingerprinting strengthens evidence for human warming role

Microwave sounding units, like the AMSU units on the Aqua satellite, shown here, can be used to take temperature measurements from different layers in the atmosphere. Ben Santer and his colleagues use this information to find a 'fingerprint' of human impact on recent climate changes. Credit: NASA

Microwave sounding units, like the AMSU units on the Aqua satellite, shown here, can be used to take temperature measurements from different layers in the atmosphere. Ben Santer and his colleagues use this information to find a ‘fingerprint’ of human impact on recent climate changes. Credit: NASA

We have left a clear climate change ‘fingerprint’ in the atmosphere, through CO2 emissions that have made air near the Earth’s surface warmer and caused cooling higher up. That’s according to Ben Santer from Lawrence Livermore National Laboratory (LLNL) in California, who started studying this fingerprint in the mid-1990s, and his expert team. They have strengthened the case by comparing satellite-recorded temperature data against the latest climate models including natural variations within Earth’s climate system, and from the sun and volcanic eruptions. Ben hopes that in the process their results will finally answer ill-tempered criticism his earlier work attracted, and lingering doubts over what causes global warming.

“There are folks out there even today that posit that the entire observed surface warming since 1950 is due to a slight uptick in the Sun’s energy output,” Ben told me. “That’s a testable hypothesis.  In this paper we look at whether changes in the sun plausibly explain the observed changes that we’ve monitored from space since 1979. The very clear answer is that they cannot. Natural influences alone, the sun, volcanoes, internal variability, either individually or in combination, cannot explain this very distinctive pattern of warming.”

That pattern emerged when scientists in the 1960s did some of the first computer modelling experiments looking at what would happen on an Earth with higher CO2 levels in the air. “They got back this very curious warming in the lower atmosphere and cooling of the upper levels of the atmosphere,” Ben explained. The effect happens because most of the gas molecules in the atmosphere, including CO2, sit relatively near to Earth’s surface. CO2’s greenhouse effect lets heat energy from the Sun reach the Earth, but interrupts some of it getting back to the upper atmosphere and outer space. Adding more CO2 by burning fossil fuels therefore warms the lower atmosphere, or troposphere, and cools the stratosphere, 6-30 miles above the Earth’s surface.  Read the rest of this entry »

Could pollution be stopping warming’s impact on rain?

A brown cloud of pollution over Phoenix, Arizona. Brown clouds of aerosol pollutant particles could be overwhelming the expected changes in rainfall arising from increasing greenhouse gas levels in the air. Credit: Flick/Flickr

A brown cloud of pollution over Phoenix, Arizona. Brown clouds of aerosol pollutant particles could be overwhelming the expected changes in rainfall arising from increasing greenhouse gas levels in the air. Credit: Flick/Flickr

Contrary to previous predictions and measurements, rain patterns have got more uniform as the world has warmed over the past 70 years. So say Michael Roderick and his teammates from Australian National University, Canberra, who’ve developed an ‘accounting system’ that looks closely at where and when rain fell. And the reason could be aerosols – clouds of pollutant particles – produced by humans. “The existing dogma is that increasing greenhouse gas concentrations in the atmosphere have raised rainfall variability,” Michael told me. “In that context, our results emphasise the importance of taking a whole system approach in trying to understand how something complex, like rainfall, is changing in different places.”

When scientists want to understand how climate has been changing over large areas, they usually look at maps of long-term average data that ignore patterns of change in time, Michael explained. When they want to look at how it’s changed over time, they usually either look at a single place or a worldwide average, which ignores patterns in where the changes are. But Michael, along with fellow scientists Fubao Sun and Graham Farquhar, wanted to find a way to link place and time.

To do this Fubao started from a common statistical test called Analysis of Variance or ANOVA. Normally it’s used to compare the effect of different “treatments” – such as a variety of temperatures – on the yield of a crop, for example. In such cases each treatment must be repeated more than once, giving different “replicates”, for the test to be valid. ANOVA can be used to give a value for variance – a measure that shows how spread out an experiment’s measurements are. Read the rest of this entry »

Soot and methane cuts promise threefold benefits

Vehicles are a significant source of black carbon and other pollutants in many countries. Credit: Caramel/flickr

Vehicles are a significant source of black carbon and other pollutants in many countries. Credit: Caramel/flickr

Limiting methane and soot emissions would save lives and keep farming output high, as well as playing an important role in fighting global warming. That’s according to some 70 scientists who have reviewed the available research on these substances for the United Nations Environment Partnership (UNEP). Such cuts were also surprisingly feasible, with just 16 ways of limiting emissions providing about 90 percent of the possible climate benefit from a list of 2000 control measures.

“We estimate that adoption of the 16 control measures we considered would save about 2 million lives a year and save 50 million tons of crops a year,” said NASA’s Drew Shindell, who led the project. “For climate, putting control measures in place could eliminate about half the warming we’ll otherwise face over the next 40 years.” Read the rest of this entry »

Atlantic cold tongue tells of humans’ climate impact

Wind waves depend on wind speed and have long been logged by ship crews. Ocean wind data corrected with wind-wave heights suggests a slow down of the southeast trade winds in the equatorial Atlantic. Credit: Image courtesy of Ship DAVID STARR JORDAN, NOAA Photo Library.

Wind waves depend on wind speed and have long been logged by ship crews. Ocean wind data corrected with wind-wave heights suggests a slow down of the southeast trade winds in the equatorial Atlantic. Credit: Image courtesy of Ship DAVID STARR JORDAN, NOAA Photo Library.

Humanity has significantly altered the climate in the tropical Atlantic between 1950 and 2009, gradually weakening the area’s trade winds, University of Hawaii at Manoa researchers say. That effect is caused by burning fossil fuels, Hiroki Tokinaga and Shang-Ping Xie explain. However, it is more directly driven by the aerosols of soot and sulfur-based particles this releases than global warming caused by the resulting CO2 greenhouse gas emissions.

Falls in aerosol emissions now look set to reverse this trend, Tokinaga notes, showing how government actions can influence the environment. “Human-produced aerosol emissions had continuously increased until the 1970s, but then they started to decrease because of legislation in North America and Europe,” he told Simple Climate. “Increased greenhouse gas forcing contributes to a broader warming of the tropical Atlantic. Another climate shift might happen when the increased greenhouse gas forcing gets stronger than the aerosol forcing in the next few decades.” Read the rest of this entry »

Greenhouse gases break temperature-rainfall link

Downpours like this one in Varanisi, India, in 1944, are set to become more common on average worldwide as the planet warms - although less so than simple physics alone suggests, and in a pattern that will mean that some areas will see decreasing precipitation. Credit: The National Archives UK

Downpours like this one in Varanisi, India, in 1944, are set to become more common on average worldwide as the planet warms - although less so than simple physics alone suggests, and in a pattern that will mean that some areas will see decreasing precipitation. Credit: The National Archives UK

Global warming is set to increase the amount of rain and snow the world gets – but researchers from the UK and Germany have confirmed this week that the proportion of water in the atmosphere becoming precipitation will decrease. “Warmer air can take up more water than colder air,” Potsdam Institute for Climate Impact Research’s Katja Frieler told Simple Climate. She underlines that global climate models – which are also closely related to models used to predict weather – show a 7 percent increase in atmospheric water vapour content per degree of global warming.

“The interesting point is that the increase in global mean precipitation is much lower,” Frieler explained, “in the range of 1 to 3 percent per degree of warming.” The difference between increases in water vapour and precipitation stems from the “energy budget” of the troposphere – the level of the atmosphere closest to the Earth’s surface. Climate modellers like Frieler treat the troposphere as a “box” where incoming and outgoing energy fluxes balance relatively quickly. When water vapour condenses to become rain it releases energy as heat. This is an energy input into the tropospheric box, which is balanced by an increased energy outflow from the troposphere. As the troposphere’s temperature rises, longwave radiation provides that increased energy outflow, allowing more precipitation.

The troposphere is the layer of the atmosphere nearest Earth. Credit: NASA

The troposphere is the layer of the atmosphere nearest Earth. Credit: NASA

However, the reason the planet is warming in the first place is because greenhouse gases trap energy from longwave radiation that would otherwise be released into space as heat. Likewise, “black carbon” soot absorbs shortwave radiation, which usually comes direct from the sun. This extra energy is what is raising global temperatures and therefore increasing water vapour content in the atmosphere. Some of the gases absorbing and trapping the energy are in the troposphere “box”. Rather than even greater outward flows compensating for this additional energy input to the troposphere, Frieler’s research shows it is being offset in a different way. “Model simulations have shown that much of this extra energy is balanced by a decrease in precipitation,” she explained. The more greenhouse gases and soot there are, the weaker the link between water vapour content in the atmosphere and precipitation, Frieler added. Read the rest of this entry »