Newsletter Digest: Global warming ‘undeniable’, phytoplankton decline, affectionate mums

More “undeniable evidence”

The State of the Climate 2009 report, released this week by the US National Ocean and Atmospheric Administration (NOAA),  confirms not only that the world is warming, but that the last decade has been the warmest on record.

In the wake of the Muir Russell review’s recent exoneration of UEA climate scientists, this report generated substantial media coverage overseas, focused largely on the executive summary’s opening statement: “global warming is undeniable”.

The report looks at 10 key climate indicators, and combines information from 48 countries (including New Zealand) and more than 300 scientists.

Some of the indicators used include sea levels and sea ice, glacier mass, ocean temperature and surface air temperature.  Of the 10, 7 would be expected to increase in a world that is warming, and 3 would be expected to decrease.  According to the report, this is exactly what is happening.

The report is of particular interest as, unlike some other climate assessment reports, it collects observed data (rather than data from models and projections), and is thus a scorecard for what’s happening to the world’s climate.

The full report and supplementary materials are available online, here, and the SMC sought comment from local climate experts on its contents.  As Dr Glenn McGregor (University of Auckland) says:

“The State of the Climate report provides yet more evidence via trends in a number of key climate change indicator variables, calculated by a number of independent climate science communities, that we are living in a period of rapidly changing climate circumstances. To what extent we can find a way to live with or adapt to these new circumstances such as the impact of atmospheric warming on human health and changes in oceanic heat on marine ecology and thus fisheries for example, presents us with one of the greatest challenges yet faced by society.”

Read more comments on the SMC website

Marine algae in decline worldwide

Global stocks of phytoplankton – the foundation of the marine food web, and drivers of the ‘biological pump’ that sequesters carbon in the deep ocean – have been falling for last hundred years, according to a study published this week in the journal Nature.

The study suggests phytoplankton have declined by nearly 40 per cent since mid-century, most probably due to rising sea surface temperatures and changing ocean conditions. The research team combined modern satellite data with decades of historical shipboard records measuring underwater visibility (which decreases with higher concentrations of phytoplankton).

The paper’s authors say that reduced phytoplankton growth is on par with ocean acidification, coral bleaching and overfishing — all major challenges facing the global marine environment.

The SMC approached local marine scientist Philip Boyd (NIWA Centre for Chemical & Physical Oceanography, University of Otago) for his comments:

“This is the most detailed study to date, over the longest time period, on whether phytoplankton stocks are declining. As phytoplankton underpin the productivity of most marine ecosystems in our exclusive economic zone (EEZ), regionally and globally, the projected progressive decrease in stocks would have major and growing ramifications for the stocks of both farmed shellfish and wild fisheries…” Continue reading