Climate News May 2017

Cholera distribution shifts in response to El Niño

Research by the John Hopkins Bloomberg School of Public Health shows that the geographic distribution of cholera cases across Africa changed significantly during El Niño years, although the total number of cases was about the same. The study used data on cholera cases from 360 separate data sets, and analysed 17,000 annual observations from 3,710 locations between 2000 and 2014.  In East Africa, cholera cases increased threefold, by about 50,000 cases, during El Niño occurrences in the 14‑year period, while at the same time there were about 30,000 fewer cases in southern Africa and significantly fewer cases in West Africa.  Because El Niño events can be predicted six to twelve months ahead, being aware of the higher cholera risk can help health authorities be better prepared.

Tiny change in Indian dietary consumption could reduce groundwater use and carbon emissions

The Lancet Planetary Health reports that groundwater use in India could be reduced significantly if dietary compositions of vegetables, fruit and meat changes by a few grams a day.  This includes reducing consumption of wheat, reducing consumption of poultry by 6.8 grams per day, increasing consumption of vegetables and legumes by 17.5 grams per day, increasing fruit consumption by 51.5 grams per day, and switching to fruits that have lower water requirements such as melon, oranges and papaya. These changes could reduce groundwater use by 30 per cent and dietary greenhouse emissions by 13 per cent.

Flammable floodplains are weak spot of Amazon forest

New research shows that floodplains in the Amazon forest are particularly prone to fire, making them the part of the forest that is most vulnerable to climate change.  A research team compared climate resilience between floodable and non-floodable areas, using satellite and field data for the entire Amazon basin along with information on over 250 forest fires.  The research suggests that the seasonally inundated areas will collapse first in response to a drying of the Amazon climate.  Previously it was thought that it was the peripheral parts of the forest that were most vulnerable.

Study reveals unexpectedly high carbon footprint of mangrove land use change

A seven-year study across five countries shows that conversion of mangroves to agricultural use results in a carbon footprint of 1,440 kg carbon dioxide equivalent for every kg of beef produced, and 1,603 kg carbon dioxide per kg of shrimp.  The study was conducted on 30 relatively undisturbed mangrove forests and 21 adjacent shrimp ponds and/or cattle pastures in Costa Rica, Dominican Republic, Honduras, Indonesia and Mexico. The researchers measured the amount of carbon stored in intact mangrove forest, greenhouse gas emissions from land use change, and the quantity of shrimp or beef produced over the life of the land use.

Extensive meltwater flow shown across Antarctica

Studies published in Nature show that there is extensive meltwater flow across Antarctica’s ice during summer.  Although meltstreams have been documented previously, this is the first continent-wide study showing their extent.  The research team analysed 70 years of data in aerial photographs from 1947 and satellite imagery from 1973, logging nearly 700 systems of interconnected ponds, channels and braided streams, some of which were found at higher altitudes than was previously thought possible.  It is not clear whether the extent and number of streams/ponds/channels have increased in all areas in this period because of sparse data at many locations, but what the study has revealed is that there is significantly more melting than was previously thought.  The direct effect of meltwater is thought to be negligible for now, but there is concern that this will change in the future.