“Everywhere we look, impacts are coming faster and harder than we would have predicted just a few years ago.”
Peter Sinclair’s recent Crock of the Week video .
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Tag: drought
Horn of Africa Drought: is it climate change?
The horrifying pictures of famine in the Horn of Africa haunt us as human tragedy, and the more because they carry with them the question of whether this has something to do with climate change. Are we going to see more and more of this kind of suffering as climate change impacts begin to mount? That’s an easier question to muse than to answer with certitude, but it deserves our attention. There is every indication that poor people are going to suffer from the impacts of climate change sooner and more harshly than the rest of us. But is the Horn of Africa famine part of that? Continue reading “Horn of Africa Drought: is it climate change?”
Catch a fire (worst year since 1816)
The extraordinary sequence of extreme weather events during the last 18 months is probably the worst run of natural disasters since 1816, when a huge volcanic eruption at Mt Tambora cooled the earth enough to cause the famous “year without a summer“, according to a powerful blog post by Weather Underground founder Jeff Masters. He runs through the list, giving details of each:
- Earth’s hottest year on record
- Most extreme winter Arctic atmospheric circulation on record
- Arctic sea ice: lowest volume on record, 3rd lowest extent
- Record melting in Greenland, and a massive calving event
- Second most extreme shift from El Niño to La Niña
- Second worst coral bleaching year
- Wettest year over land
- Amazon rainforest experiences its 2nd 100-year drought in 5 years
- Global tropical cyclone activity lowest on record
- A hyperactive Atlantic hurricane season: 3rd busiest on record
- A rare tropical storm in the South Atlantic
- Strongest storm in Southwestern U.S. history
- Strongest non-coastal storm in U.S. history
- Weakest and latest-ending East Asian monsoon on record
- No monsoon depressions in India’s Southwest Monsoon for 2nd time in 134 years
- The Pakistani flood: most expensive natural disaster in Pakistan’s history
- The Russian heat wave and drought: deadliest heat wave in human history
- Record rains trigger Australia’s most expensive natural disaster in history
- Heaviest rains on record trigger Colombia’s worst flooding disaster in history
- Tennessee’s 1-in-1000 year flood kills 30, does $2.4 billion in damage
Russian roulette with a rainforest
I reported in a November post that it appeared likely that the 2010 Amazon drought was even more severe than the 2005 drought, itself identified as a 1-in-100-year event. Now Simon Lewis of Leeds University and Paulo Brando of Brazil’s Amazon Environmental Research Institute (IPAM) and others have published a paper in Science with rainfall analysis showing that the 2010 drought was indeed more widespread and severe than that of 2005.
The 2005 drought killed billions of trees within the rainforest. On the ground monitoring showed that these forests stopped absorbing CO2 from the atmosphere, and as the dead trees rotted they released CO2 to the atmosphere.
The press release reports that this new research, co-led by Dr Lewis and Brazilian scientist Dr Paulo Brando, used the known relationship between drought intensity in 2005 and tree deaths to estimate the impact of the 2010 drought.
They predict that Amazon forests will not absorb their usual 1.5 billion tonnes of CO2 from the atmosphere in both 2010 and 2011, and that a further 5 billion tonnes of CO2 will be released to the atmosphere over the coming years once the trees that are killed by the new drought rot. For context, the United States emitted 5.4 billion tonnes of CO2 from fossil fuel use in 2009.
They can’t be sure, of course, until they have completed forest measurements on the ground and they describe their results as an initial estimate, one which incidentally does not include any emissions from fires which can be extensive during hot and dry years.
The danger is that this could be a precursor of the Amazon rainforest no longer playing the part it does in regulating atmospheric CO2. Simon Lewis:
“Two unusual and extreme droughts occurring within a decade may largely offset the carbon absorbed by intact Amazon forests during that time. If events like this happen more often, the Amazon rainforest would reach a point where it shifts from being a valuable carbon sink slowing climate change, to a major source of greenhouse gasses that could speed it up.”
Of course it is possible that the two droughts are just an unusual natural variation, but Lewis points out that they are consistent with climate models which project a grim future for Amazonia.
Tropical ecologist Daniel Nepstad is Director of International Programs at IPAM and one of the paper’s authors. He was interviewed a couple of months ago during the Cancún conference.
“It’s about as bad as we’ve seen. I’ve been working in the Amazon for about 25 years now, and I haven’t seen anything like it. We thought we had the worst drought of the century in 2005, and this one is worse.”
The interviewer comments that the drought in 2005 was called a once-in-a-century drought, just five years ago.
“I know. And, there was a drought in 2007 that didn’t even capture any immediate attention, it wasn’t even worth it because drought is really becoming part of the fabric of the Amazon.”
The cause?
“You know, statistically, it’s just very hard to take an individual event like this mega-drought of the Amazon, and say that it is a direct cause of climate change. But, with both this and the 2005 and the 2007 drought, they’re all consistent with the scenario of increasing accumulation of greenhouse gasses in the atmosphere.”
How does the drought affect the rainforest?
“The forest actually makes the rain in the Amazon. By the end of the dry season, a lot of Amazon trees are sucking water from the soil- it could be 60 feet beneath the ground surface. So, they’re going way down deep to get that water, so that they can keep their green lush canopy, even though they’ve been deprived of water for a few months. And, that water going into the atmosphere makes the clouds that make the rain. Similarly, the rain coming down, if it weren’t for that rain, if those dry seasons got longer on a permanent basis, then that forest would cease to be. It would be replaced by grassy vegetations, savannahs, woodlands and scrub that would burn periodically, and that would look very different and have far fewer species.”
What are scientists supposed to think when confronted with possibilities such as those represented by recent Amazon droughts? That it will be interesting to see whether this is the start of a trend which would confirm predictions of the impacts of increasing greenhouse gases? That without further evidence they must be careful not to sound alarmist? In fact Simon Lewis and Daniel Nepstad are properly cautious, acknowledging that as scientists they can’t say with certainty that these droughts are part of human-caused climate change. But they are also very aware of the magnitude of the danger represented by the droughts if they are the result of increased greenhouse gas emissions. A statement by Lewis reported in a Guardian article expresses succinctly why we can’t just wait to see whether further evidence accumulates.
“We can’t just wait and see because there is no going back. We won’t know we have passed the point where the Amazon turns from a sink to a source until afterwards, when it will be too late.”
In other words the possible consequences are so dire that it is reckless to risk them.
“If greenhouse gas emissions contribute to Amazon droughts that in turn cause forests to release carbon, this feedback loop would be extremely concerning. Put more starkly, current emissions pathways risk playing Russian roulette with the world’s largest rainforest.”
That’s a serious warning from a scientist. And the Amazon is not an isolated case. Ove Hoegh-Guldberg, in the presentation Gareth has recently posted, is convinced with good reason that ocean ecosystems are already being seriously impacted under current elevated levels of atmospheric CO2 and that a 450 ppm level will be disastrous for ocean life and consequently for us. The world’s ice is clearly under assault from warming, with the likelihood of sea level rise of fearful consequence to human populations, as scientists like James Hansen now regularly warn. The list is long.
We’re playing Russian roulette with more than the rainforests, and the revolver has more than one chamber loaded. The longer we take to start reducing emissions the more we shorten the odds
I wish it would rain
We (or at least some of us) rightly feel apprehension and alarm at the prospect of melting glacial and polar ice. There are new reminders that we should be equally alarmed at the prospect of Amazonian drought. Joe Romm has written a lengthy post on Climate Progress drawing attention to the 2010 drought which may prove more widespread and severe than the 2005 drought, itself identified as a 1-in-100-year type event. He quotes an email to that effect from forest scientist and Amazon expert Simon Lewis (he of the Sunday Times fightback and subsequently granted apology).
Lewis recommends an article in the Global Post which is well worth reading. It refers to three scientists. Oliver Phillips, a tropical ecology professor at the University of Leeds, speaks of his concern that parts of the Amazon may be approaching a threshold point beyond which the eco-system can’t go. He led a team of researchers who studied the damage caused by the 2005 drought which caused a massive die-off of trees and led to the forest expelling carbon dioxide rather than absorbing it. He’s worried that another severe drought is following so soon after the last one. Greg Asner, an ecologist at the Carnegie Institution for Science, points out that some tropical forests in the world now are starting to be exposed to temperatures they’ve never experienced. His studies show that higher temperatures and shifts in rainfall could leave as much as 37 percent of the Amazon so radically altered that the plants and animals living there now would be forced to adapt, move or die. Foster Brown, an environmental scientist at the federal university in the Brazilian state of Acre, comments that drought has made ecosystems so dry that instead of a being a barrier to fire, the forest became kindling.
Nikolas Kozloff’s book No Rain in the Amazon which I reviewed earlier this year refers to much-cited scientist Philip Fearnside of Brazil’s National Institute for Research in the Amazon, who for some years has observed the connection between drought and El Niño-like conditions which are expected to become more frequent with continued global warming. He too is concerned that the Amazon might dry out and be placed in jeopardy as a result of climate change. Kozloff also reports the belief of some researchers that warming sea surface temperatures in the tropical North Atlantic Ocean are linked to Amazon drought.
In an October press release Brazil’s Amazon Environmental Research Institute (IPAM) comments:
“The drought of 2010 still hasn’t ended in the Amazon and could surpass that of 2005 as the region’s worst during the past four decades… Even if this doesn’t occur, the forest will have already experienced three extreme dry spells in just 12 years, two of which occurred during the past five years: 1998, 2005 and 2010. And this is not including the drought of 2007, which affected only the Southeastern Amazon and left 10 thousand sq. km. of forest scorched in the region…`The Amazon that had wet seasons so well-defined that you could set your calendar to them – that Amazon is gone,’ says ecologist Daniel Nepstad of IPAM…”
Deforestation of the Amazon by humans has long been a major international concern, and Simon Lewis’s communication with Jo Romm indicates that there is a degree of good news on that front in that since 2005 deforestation rates have been radically reduced. But the droughts are bad news. They kill trees and promote damaging fires, “potentially leading to a drought-fire-carbon emissions feedback and widespread forest collapse”. Lewis expresses particular concern that while two unusual droughts clearly don’t make a trend, they are consistent with some model projections made well before 2005: “that higher sea surface temperatures increase drought frequency and intensity, leading later this century to substantial Amazon forest die-back.”
Hot Topic commenter Tony on a previous post linked to an Al Jazeera video clip (which I’ve posted below), with the observation that if anything should motivate a sense of urgency in Cancun, what it portrayed should. Simon Lewis also linked what may be happening in the Amazon to the Cancun conference. Not with any great expectation, but with a dry reminder that the risks to which we are exposing humanity don’t diminish because we ignore them. “While little is expected of the climate change talks in Cancun next week, the stakes, in terms of the fate of the Amazon are much higher than they were a year ago in Copenhagen.”
I hope it doesn’t appear as incidental if I note before concluding that the droughts affect not only the forest and through it the welfare of the whole planet but also the local populations whose livelihood and wellbeing is jeopardised. The Global Post article reports the anxiety of village chief Mariazinha Yawanawa. Her people are sustained by the forest. They hunt in the woods, fish the rivers and grow crops in the clearings where they live. “Everything has changed. We don’t know when we can plant. We plant and then the sun kills everything. If it continues like this, we expect a tragedy
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