Tag: heatwaves

Extremes report 2013: NZ drought and record Aussie heat made worse by warming

The latest climate extremes report finds that 9 out of 16 extreme weather events from last year were influenced by climate change. In particular, the conditions that led to New Zealand’s severe North Island drought — the worst for 41 years, estimated to have cost the economy NZ$1.3 billion — were made more likely by the effects of continued warming. Australia’s hottest ever year and run of record-breaking heatwaves also had humanity’s fingerprints all over it. The new research — Explaining Extreme Events of 2013 from a Climate Perspective [pdf] — published as a special edition of the Bulletin of the American Meteorological Society, is the latest in a series of reports designed to look at weather extremes soon after they happen, and look for signs of the influence of climate change.

The NZ paper, The role of anthropogenic climate change in the 2013 drought over North Island, New Zealand by Luke Harrington, Suzanne Rosier, Sam M. Dean, Stephen Stuart, and Alice Scahill (page s45 in the pdf), finds that a long term trend towards increasing summer high pressure systems over the North Island — seen in climate models as the system warms — has increased the risk of drought substantially.

No fewer than 5 studies in the new report found clear links between Australia’s record-breaking 2013 heat and the influence of human-induced warming, as explained by The Conversation here.

Climate change is already increasing the likelihood of heatwaves occurring in Australia and the temperatures we experience during these heatwaves. Extremely hot months, seasons and years are already more likely in Australia.

This human handprint will likely increase the future risk of extremely warm days, months, season and years in Australia. We will likely also see an increase in the risk of heatwaves and dry conditions acting in combination with heat to produce drought.

A summary of the report’s contents is available from NOAA, Climate Central has a very nice timeline, and The Guardian does it with pictures. Strangely, given the subject matter, only TV3 picked up on the NZ drought link (basing their story on a press release from the Green Party), while the NZ Herald chose to run an AFP story that led with the Aussie heatwaves and only mentioned the NZ drought in passing. Neither NIWA nor VUW chose to issue press releases about the study, despite its obvious newsworthiness and relevance to the NZ agricultural community.

[Update 2/10: Stuff.co.nz finally covers the story, with quotes from NIWA’s Sam Dean.]

IPCC WG2 impacts report released: fire, floods and rising seas in all our futures

After the usual run of late nights and argument, the IPCC has released the second part of its fifth report — the Working Group 2 report on climate impacts and risks management. Commenting on the report, VUW climate scientist Professor Tim Naish said “this latest report makes it quite clear that New Zealand is under-prepared and faces a significant ‘adaptation deficit’ in the context of the projected impacts and risks from global average warming of +2 to 4°C by the end of the century.”

The IPCC identifies eight key regional risks for New Zealand and Australia:

  • significant impacts on coral reefs in Australia as oceans warm and acidify
  • loss of montane ecosystems in Australia, as climate warms and snow lines rise
  • increased frequency of and intensity of flooding in NZ and Australia
  • water resources in Southern Australia will be under increased pressure
  • more intense heatwaves will bring increased death rates and infrastructure damage
  • increasing risks of damaging wildfires in New Zealand and southern Australia
  • increased risks to coastal infrastructure and ecosystems from sea level rise
  • risk of severe drying in parts of Australia could hit agricultural production

For New Zealand, extreme weather events such as flooding and heatwaves are expected to increase in frequency and severity, and rainfall is expected to increase on the already wet west coast and decrease in the east and north east. Sea level rise of up to one metre is expected to cause significant problems for coastal communities.

VUW’s Jim Renwick points to sea level rise as a big issue:

Every 10cm of rise triples the risk of a given inundation event, and we are expecting something like a metre of rise this century. That would mean today’s 1-in-100 year event occurs at least annually at many New Zealand coastal locations. New Zealand has a great deal of valuable property and infrastructure close to the coast that will be increasingly at risk as time goes on.

The Summary for Policymakers of the WG2 report is available here (pdf), and the final draft of the full report can be downloaded from this page. The Australia and New Zealand chapter (25) is here (pdf) and the Small Islands (Ch 29) here (pdf).

A huge amount of coverage of the report’s findings has already hit the net, and there will be more to come. Check out The Guardian‘s take on the five key points in the report, The Conversation’s examination of climate health risks, Graham Readfearn’s commentary on 25 years of IPCC warnings, and Peter Griffin’s look at the prospects for agriculture. I’ll have a post about the NZ political response to the report tomorrow.

Where the wind blows, it rains: Arctic warming and wacky jetstream ruins European summers

The dramatic loss of summer sea ice in the Arctic has prompted a lot of research interest in the way that this is affecting weather patterns around the northern hemisphere. The latest contribution is Influence of Arctic sea ice on European summer precipitation, by Dr James Screen of the University of Exeter [PhysOrg]. In this “video abstract”, he explains how reductions in Arctic sea ice affect the position of jetstream — the ribbon of winds winding around the planet that guides weather systems — bringing more summer storms to Western Europe, and a recent run of record-setting wet summers to the UK. But as he points out, the effects are planet-wide:

The impacts are not just over northwest Europe. Actually in the model, what we find is that whilst the sea ice loss increases rainfall over northwest Europe, we actually find drier conditions over Mediterranean Europe. Also the jet steam shifts over North America, which can have implications for the weather there too.

Dr Screen’s study underlines a point that I have been making for some time: rapid climate change is not something theoretical that will happen in the future — it’s happening now and we’re feeling the effects. Warming in the Arctic is driving sea ice loss, and the atmospheric consequences are changing the shape of the weather right round the northern half of the planet.

Also interesting, and also looking at jetstream patterns is Probability of US heat waves affected by a subseasonal planetary wave pattern, in which the authors find that US heatwaves might be predictable 15-20 days earlier than at present by monitoring a particular jetstream wave pattern. [Science Daily]

It’s worth noting that an especially vigorous jetstream directed and helped to intensify the recent huge European storm that hammered the UK, Germany and Denmark, killing 16 people and causing huge amounts of damage. Christopher Burt at WeatherUnderground provides a handy overview of the storm that has four names — St Jude, Christian, Simone and Carmen. The storm centre moved 2,000 km in 26 hours, a remarkable pace of 77 kph.

Beatin’ the heat: cut carbon or we’re cooked

The area of land affected by extreme heatwaves is expected to double by 2020 and quadruple by 2040, and there’s no way we can stop it happening according to a new paper by Dim Coumou and Alexander Robinson – Historic and future increase in the global land area affected by monthly heat extremes (Environmental Research Letters, open access). However, the researchers find that action to cut emissions can prevent further dramatic increases in heat extremes out to the end of the century.

The paper’s made headlines around the world — see The Guardian, Independent, and Climate Central — most focussing on the inevitability of more, and more intense, heat events in the near future. Dana Nuccitelli at The Guardian provides an excellent discussion of the science behind the new paper so, to avoid reinventing the wheel, I’m going to focus on a fascinating chart from the paper, and then ponder the implications for climate policy.

Continue reading “Beatin’ the heat: cut carbon or we’re cooked”

I think it’s going to rain today (when it’s wet, it’s very very wet)

I took Rosie the truffle machine for a walk around the farm just before dark yesterday. We were both a bit stir-crazy after four days of cold, cold rain and a couple of days of screaming southerlies that brought snow to our hills. The ground passed field capacity at the beginning of last week, when an atmospheric river brought torrential downpours and flooding to much of the South Island. Now the soil is sodden, quivering with water and oozing mud at every footstep. Every drop of extra rain is taking that mud and sluicing it down to the river. A stream runs through my black truffle plantation. I spent this afternoon digging a drainage trench. Truffles don’t enjoy sitting in water. My crop might rot. The Waipara is roaring along at the bottom of our cliff at about 50 cumecs ((Cubic metres per second.)), an impressive sight for a river that normally dribbles down to the sea at under a cumec. It peaked last week at about 110 cumecs. The riverbed will have been reshaped. But we got off lightly.

Over the last couple of days the New Zealand news has been dominated by extreme weather. The southerly storm that soaked us also battered Wellington and brought deep snow ((The Mt Hutt ski field got 2.8 meters of snow — just over 9 feet in the old money — a record start to the season. Take a look at the green line on their snow graph to get some sense of the context.)) to much of the South Island. It made for compelling pictures. But what’s going on elsewhere in the world is even more dramatic:

Continue reading “I think it’s going to rain today (when it’s wet, it’s very very wet)”