Science

For the first time scientists have demonstrated the impact of climate change on ocean warming and sea surface temperatures affecting global fisheries stocks. Previous studies were limited to individual fisheries. The changes have been occurring clearly since the 1970s, the scientists say. The implications of this research raises the need for timely changes in fisheries management practices and adaptation plans for communities dependant on fishing, particularly climate vulnerable developing countries in the tropics.

"Given global fisheries contribute hugely to the world's economy and food security, this is a significant finding," said co-author Dr Reg Watson from the University of Tasmania's specialist Institute for Marine and Antarctic Studies."We are no longer talking about future hypotheticals - we are talking about impacts on a global scale that we can already demonstrate."

Previous research by Dr Watson published last year demonstrated that marine fishes are now smaller in size. "Last year we showed that one of the consequences of climate change and excessive fishing is that globally marine fishes are smaller," said Dr Watson.

The paper - Signature of ocean warming in global fisheries catch - was published in Nature on 15 May 2013. The study was lead by Assistant Professor William Cheung, University of British Columbia, with collaboration from Professor Daniel Pauly and Dr Reg Watson.

I wrote about a related issue on the Velocity of climate change imperiling ocean diversity, particularly with regard to Australia, in January 2012.

To most of us, what is hidden beneath the waves of our coastal environment remains invisible and is little thought about or cared about. Yet seagrass meadows, though hidden from our direct view, contribute valuable ecological services supporting valuable fish nurseries, as food for dugongs and turtles, and as a highly efficient blue carbon sink sequestering carbon. 

A new study of the seagrass meadows in Moreton Bay, Queensland found that a significant proportion of valuable seagrass habitats would be lost without action to offset the affects of climate change. "The area of seagrass habitat was predicted to decline by 17% by 2100 under a scenario of SLR of 1.1 m." said the study. 

Lead author Dr Megan Saunders from UQ's Global Change Institute said "Seagrass meadows not only help to slow climate change by sucking up a large portion of the world's plant-stored carbon, but they also benefit livelihoods, food security, fisheries, biodiversity, shoreline protection and other ecosystem services,"

A recent study looking into regional tropical cyclone formation conditions in the east and central Pacific has projected that 2 to 3 times more tropical cyclones (Hurricanes) are likely to hit Hawaii in the later part of this century.

James Ross island, Antarctic PeninsulaThis study analysing an Antarctic Peninsula ice core from James Ross island has determined that there has been a ten fold increase in melt intensity over the last 600 years. I reported recently that the Antarctic Peninsula summer melt season prolonged by global warming according to research from the British Antarctic Survey.

"The warming has occurred in progressive phases since about AD 1460, but intensification of melt is nonlinear, and has largely occurred since the mid-twentieth century. Summer melting is now at a level that is unprecedented over the past 1,000 years. We conclude that ice on the Antarctic Peninsula is now particularly susceptible to rapid increases in melting and loss in response to relatively small increases in mean temperature." concludes the study.

It seems the genetics of the Antarctic Octopus is showing us how fragile the West Antarctic Ice sheet (WAIS) may be with global warming. It raising questions about the ice sheet susceptibility to collapse.

NASA image: Rossby Waves of the JetstreamA series of major extreme weather events in the Northern hemisphere including the heatwave in the United States in 2011, the Russian heatwave of 2010, the Pakistani floods of 2010 have now been attributed to a common physical cause. The scientists suggest in a new scientific study that man-made climate change repeatedly disturbs the patterns of atmospheric flow - the atmospheric Rossby waves of the jet stream - around the globe's Northern hemisphere through a subtle resonance mechanism.

"An important part of the global air motion in the mid-latitudes of the Earth normally takes the form of waves wandering around the planet, oscillating between the tropical and the Arctic regions. So when they swing up, these waves suck warm air from the tropics to Europe, Russia, or the US, and when they swing down, they do the same thing with cold air from the Arctic," explains lead author Vladimir Petoukhov.

At what point might we trigger a permafrost tipping point? New research from the caves of Siberia points to a threshold temperature of just 1.5 degrees celsius. At that temperature we could see large swathes of permafrost across Siberia melting resulting in the release of more than 1,000 gigatons of carbon and methane. This would be a substantial climate feedback resulting in even greater global warming. There would also be substantial damage to natural and human environments and structures.

And we are already halfway there to warming the world by 1.5C, with an estimated global temperature rise since the Nineteenth century of between 0.7 and 0.8 degrees C. There is already enough inertia in the climate system to carry us over this threshold. Which makes every attempt to reduce carbon emissions, and the use of fossil fuels, as worthwhile to limit the permafrost thaw.

Related: Methane and CO2 in thawing Arctic permafrost a climate tipping point | "We do have an emergency" - Arctic Methane Feedback amplifying warming | Arctic Permafrost thawing raising CO2 levels

Labour capacity reduced due to heat stress as temperature and humidity rises with Climate ChangeClimate change will result in hotter and more humid environment for the tropics and mid latitudes resulting in increasing economic costs of reduced work capacity due to heat stress. The study by NOAA scientists said work capacity has already reduced by 10 percent due to extreme heat in summer months. This is likely to double to 20 per cent by 2050.

One of the physical properties of warmer air is that it can hold more moisture. So in hot weather atmospheric humdity can be more extreme. But there are physiological limits of human health in coping with temperature extremes. In 2010 Scientists outlined health limits of heat stress with Climate Change. The scientific paper by Steven Sherwood from the University of NSW and Professor Matthew Huber from Purdue University - 'An Adaptability Limit to Climate Change Due to Heat Stress' outlined the health adaptation limits of the human body.

A worldwide review of global rainfall data led by the University of Adelaide has found that the intensity of the most extreme rainfall events is increasing across the globe as temperatures rise.

The diminishing Arctic sea-ice extent is resulting in changes in how greenhouse gases interact between the land, ocean and atmosphere according to a new study.

"Changes in the balance of greenhouse gases can have major consequences because, globally, plants and the oceans absorb around half of the carbon dioxide that humans release into the air through the use of fossil fuels. If the Arctic component of this buffer changes, so will the amount of greenhouse gases in the atmosphere", says Dr Frans-Jan Parmentier, a researcher at Lund University, Sweden, and lead author of the study.