Carbon pricing, one year on: independent expertise is crucial

Climate change is too important a topic to leave to politicians. Canberra should listen to the real experts – the Climate Change Authority

It’s time Australia moved to full-blown emissions trading scheme

Ending the carbon tax and moving to emissions trading – as Kevin Rudd is reportedly considering – is the right thing to do

Monday 1 July 2013 18.55 EST guardian.co.uk

• Jump to comments (8)

Environment

• Emissions trading ·
• Carbon tax

World news

• Australia ·
• Kevin Rudd ·
• Tony Abbott

Series

• Guardian Environment Blogs

More from Southern crossroads on

Environment

• Emissions trading ·
• Carbon tax

World news

• Australia ·
• Kevin Rudd ·
• Tony Abbott

Series

• Guardian Environment Blogs

More blogposts

The ability to forecast how ENSO will respond to global warming thus matters greatly to society. Providing accurate predictions, though, is challenging because ENSO varies naturally over decades and centuries. Instrumental records are too short to determine whether any changes seen recently are simply natural or attributable to human-made greenhouse gases. Reconstructions of ENSO behavior are usually missing adequate records for the tropics where ENSO develops.

Help is now underway in the form of a tree-ring record reflecting ENSO activity over the past seven centuries. Tree-rings have been shown to be very good proxies for temperature and rainfall measurements. An international team of scientists spearheaded by Jinbao Li and Shang-Ping Xie, while working at the International Pacific Research Center, University of Hawaii at Manoa, has compiled 2,222 tree-ring chronologies of the past seven centuries from both the tropics and mid-latitudes in both hemispheres. Their work is published in the June 30, 2013 online issue of Nature Climate Change.

The inclusion of tropical tree-ring records enabled the team to generate an archive of ENSO activity of unprecedented accuracy, as attested by the close correspondence with records from equatorial Pacific corals and with an independent Northern Hemisphere temperature reconstruction that captures well-known teleconnection climate patterns.

These proxy records all indicate that ENSO was unusually active in the late 20th century compared to the past seven centuries, implying that this climate phenomenon is responding to ongoing global warming.

“In the year after a large tropical volcanic eruption, our record shows that the east-central tropical Pacific is unusually cool, followed by unusual warming one year later. Like greenhouse gases, volcanic aerosols perturb the Earth’s radiation balance. This supports the idea that the unusually high ENSO activity in the late 20th century is a footprint of global warming,” explains lead author Jinbao Li.

“Many climate models do not reflect the strong ENSO response to global warming that we found,” says co-author Shang-Ping Xie, meteorology professor at the International Pacific Research Center, University of Hawaii at Manoa and Roger Revelle Professor at Scripps Institution of Oceanography, University of California at San Diego. “This suggests that many models underestimate the sensitivity to radiative perturbations in greenhouse gases. Our results now provide a guide to improve the accuracy of climate models and their projections of future ENSO activity. If this trend of increasing ENSO activity continues, we expect to see more weather extremes such as floods and droughts.”

• DENIED: Steve Turner’s plan for his property at Belmont South has been hampered by the council’s sea-level-rise measure. Picture: Peter Stoop

Climate change may result in the inability of low-elevation forests which are located in arid regions to regenerate, according to new research from Oregon State University.

“A decade after a stand-replacement forest fire on the Metolius watershed in Central Oregon, almost no trees have begun to regenerate on one of the dry sites at lower elevation.”
Image Credit: Oregon State University

With rising temperatures and increasing aridity, many regions may see the disappearance of their forests. “Predicted increases in temperature and drought in the coming century may make it more difficult for conifers such as ponderosa pine to regenerate after major forest fires on dry, low-elevation sites, in some cases leading to conversion of forests to grass or shrub lands.”

The researchers “concluded that moisture stress is a key limitation for conifer regeneration following stand-replacing wildfire, which will likely increase with climate change. This will make post-fire recovery on dry sites slow and uncertain. If forests are desired in these locations, more aggressive attempts at reforestation may be needed.”

The new research was based on work “done in a portion of the Metolius River watershed in the eastern Cascade Range of Oregon, which prior to a 2002 fire was mostly ponderosa pine with some Douglas-fir and other tree species. The research area was not salvage-logged or replanted following the severe, stand-replacing fire.”

“A decade after this fire, there was almost no tree regeneration at lower, drier sites,” said Erich Dodson, a researcher with the OSU Department of Forest Ecosystems and Society. “There was some regeneration at higher sites with more moisture. But at the low elevations, it will be a long time before a forest comes back, if it ever does.”

The Oregon State University press release continues:

Similar situations may be found in many areas of the American West in coming decades, the researchers say, and recruitment of new forests may be delayed or prevented — even in climate conditions that might have been able to maintain an existing forest. While mature trees can use their roots to tap water deeper in the soil, competition with dense understory vegetation can make it difficult for seedlings to survive.

Openings in ponderosa pine forests created by wildfire have persisted for more than a century on harsh, south-facing slopes in Colorado, the researchers noted in their report. And fire severity is already increasing in many forests due to climate change — what is now thought of as a drought in some locations may be considered average by the end of the next century.

If trees do fail to regenerate, it could further reduce ecosystem carbon storage and amplify the greenhouse effect.

Restoration treatment including thinning and prescribed burning may help reduce fire severity and increase tree survival after wildfire, as well as provide a seed source for future trees. These dry sites with less resilience to stand-replacing fire should be priorities for treatment, if maintaining a forest is a management objective.

Higher-elevation, mixed conifer forests in less moisture-limited sites may be able to recover from stand-replacing wildfire without treatment.

The new research was just published in Forest Ecology and Management.