Saturday, May 18, 2013

Common plants and animals facing dramatic biodiversity decline from climate change

Closeup 2 - Matted Flax-lily (Dianella amoena) at Bababi Djinanang native grassland Fawkner

While much scientific and public attention has focussed on the many species endangered or on the brink of extinction, the impacts of climate change on species biodiversity are much larger. A landmark study looking at nearly 50,000 common species with widespread ranges has determined that half of these animals and two thirds of the examined plant species will lose more than half their range in the next 70 years, by 2080, if nothing is done to slow down the rate of global warming through cutting carbon emissions.


There is presently underway a biodiversity crisis with habitat loss and climate change causing the 6th mass extinction. Landuse and vegetation policy changes such as the recent Queensland Land clearing changes, exacerbate climate change impacts on biodiversity. It has been shown that preservation of plant biodiversity provides a crucial buffer to negative effects of climate change and preservation of biodiversity for many common species. Similarly, logging of native bushland and forests such as the Victorian Central Highland and East Gippsland forests destroys important wildlife refugia which also act as important carbon sinks. Victoria's forests are amoung the world's most carbon dense.

While there has been targeted research on how climate change impacts certain endangered and rare species, there have been few broad studies of how an increase in global temperature and climate change will affect more common species distribution and range.


The study - Quantifying the benefit of early climate change mitigation in avoiding biodiversity loss - was published in Nature Climate Change. An international team of scientists from the UK, Australia and Columbia was lead by Dr Rachel Warren from the University of East Anglia's (UEA) school of Environmental Sciences and the Tyndall Centre for Climate Change Research. Other authors include Associate Professor Jeremy VanDerWal at James Cook University in Australia and Dr Jeff Price from UEA's school of Environmental Sciences and the Tyndall Centre. JCU's Professors Ian Atkinson and Stephen Williams were also involved. J. Ramirez-Villegas & A. Jarvis contributed from the CGIAR Research Program on Climate Change, Agriculture and Food Security from the International Centre for Tropical Agriculture (CIAT), Cali, Colombia.

While this looks disastrous for species diversity, the researchers emphasise that acting quickly to mitigate climate change could reduce losses by 60 per cent and buy an additional 40 years for species to adapt.


"Our analyses indicate that without mitigation, large range contractions can be expected even amongst common and widespread species, amounting to a substantial global reduction in biodiversity and ecosystem services by the end of this century. Prompt and stringent mitigation, on the other hand, could substantially reduce range losses and buy up to four decades for climate change adaptation." the study authors say in the paper.

In a statement Dr Warren commented:

"This broader issue of potential range loss in widespread species is a serious concern as even small declines in these species can significantly disrupt ecosystems," she said.

"Our research predicts that climate change will greatly reduce the diversity of even very common species found in most parts of the world. This loss of global-scale biodiversity would significantly impoverish the biosphere and the ecosystem services it provides.

"We looked at the effect of rising global temperatures, but other symptoms of climate change such as extreme weather events, pests, and diseases mean that our estimates are probably conservative. Animals in particular may decline more as our predictions will be compounded by a loss of food from plants.

"There will also be a knock-on effect for humans because these species are important for things like water and air purification, flood control, nutrient cycling, and eco-tourism.

"The good news is that our research provides crucial new evidence of how swift action to reduce CO2 and other greenhouse gases can prevent the biodiversity loss by reducing the amount of global warming to 2 degrees Celsius rather than 4 degrees.

"This would also buy time - up to four decades - for plants and animals to adapt to the remaining 2 degrees of climate change."

"Prompt and stringent action to reduce greenhouse gas emissions globally would reduce these biodiversity losses by 60 per cent if global emissions peak in 2016, or by 40 per cent if emissions peak in 2030, showing that early action is very beneficial," Dr Warren said.

"This will both reduce the amount of climate change and also slow climate change down, making it easier for species and humans to adapt."


Caption: Fig. S3a-f. Species richness of animals (a, c) and plant (b, d) species present in the GBIF network in the 2080s under realistic dispersal for the stringent mitigation case in which global greenhouse gas emissions peak in 2030 and are subsequently reduced at 5% annually (c, d) compared with the no mitigation case SRES A1B (a, b). Panels (e, f) show the species richness change that is avoided by such mitigation. White areas are those where no data exist in the GBIF network. From Warren et al Supplementary Information.

The study defined the climate 'niche' occupied by each species, based on temperature and rainfall where they live now, and mapped the areas that would remain suitable for them according to various scenarios of future climate change.

High species loss projected for Sub-Saharan Africa, Central America, Amazonia and Australia


According to impact projections, the study says that plants, reptiles and particularly amphibians are expected to be at highest risk. Sub-Saharan Africa, Central America, Amazonia and Australia would lose the most species of plants and animals. And a major loss of plant species is projected for North Africa, Central Asia and South-eastern Europe.


Table S2a: Relative importance of climatic driving variables across all taxa and species modelled in MaxEnt (a) proportion of species in each taxa which are more strongly driven by temperature related variables
Taxon Total number modeled Number more strongly affected by temperature % more strongly affected by temperature related factors
Plants 43,578 27691 64%
Mammals 1,168 790 67%
Birds 3,059 2285 54%
Reptiles 663 423 63%
Amphibians 492 270 55%
ALL 48,960 31,459 64%

The study was based on the Global Biodiversity Information Facility (GBIF), which collates information and data on location and distribution of species. The GBIF dataset includes around 400 million biodiversity records collected from hundreds of volunteers, scientific expeditions and natural history collections. The GBIF was established in 2001 as an intergovernmental scientific infrastructure aimed at providing free and open access to biodiversity data, via the Internet.

The authors examined 170 million occurrence records from 200 data providers. Through a process of verifying locational consistency and discarding conflicting records, the number of species in the study was reduced to 48,786. Each species had their environmental niche analyzed, with Species records considered as outliers further examined

"Whilst there are gaps in the available data, GBIF provides a source to allow researchers to identify the potential patterns of change across the widest range of species and areas possible." said the authors.

Co-author Dr Jeff Price said: "Without free and open access to massive amounts of data such as those made available online through GBIF, no individual researcher is able to contact every country, every museum, every scientist holding the data and pull it all together. So this research would not be possible without GBIF and its global community of researchers and volunteers who make their data freely available."

Rates of Dispersal for keeping up with the Velocity of climate change

Dispersal rates for species were also taken into account as species attempt to keep within their climate envelope in their ecological niche by either moving towards the pole or higher in elevation.


"The projected velocity of temperature change over the earth's surface is estimated to be 0.42 km/yr (0.11-0.46 km/yr) for the 2050s, whilst observations over the period 1950-2009 already show median velocities of 2.7 km/yr (on land) and 2.2 km/yr (in the ocean) over the period 1950-2009." argue the authors based on previous studies on the impact of species biodiversity from the velocity of climate change.

Birds have arguably the greatest capacity to disperse in conjunction with the velocity of climate change. "In the UK, 12 bird species have been moving northwards at a rate of approximately 1 km/year. Huntley gives dispersal rates of 0.2-2 km/year for birds, whilst in Finland some species have been moving northwards about 19 km in 12 years (i.e. at 1.6 km/year); whilst Devictor et al report that European bird communities are shifting at a rate of 37±3 km in an 18 year period, or approximately 2 km/year. Hence for birds we chose a realistic dispersal rate of 1.5 km/year, and an optimistic one of 3 km/year." explain the authors.

Mammals are suggested to have a similar dispersal rate to birds.

Reptiles and amphibians dispersal capacity is estimated to be very poor, but this is based upon a limited number of studies. The authors estimated a realistic dispersal rate for reptiles at 0.1 km/year, and assumed that amphibians would also be thus constrained. An optimistic dispersal rate for reptiles and amphibians was set at 0.5 km/year. certainly reptiles face a bleak future. Scientists estimate that for lizard diversity "by 2080 local extinctions are projected to reach 39% worldwide, and species extinctions may reach 20%.". The 2010 scientific paper by Sinervo et al - Erosion of Lizard Diversity by Climate Change and Altered Thermal Niches - came to the conclusion that "lizards have already crossed a threshold for extinctions caused by climate change."


Plant dispersal tends to be quite slow, but seed dispersal rates vary widely. According to the authors some plants such as creeping of stems disperse on average only 0.1 m per year (1 m/decade). But other plants which are aided by birds dispersing seed can move on average 500 m/year (5 km/decade). For wind dispersal estimates of 40-300 m/year (0.4-3 km/decade) , while ant and rodent dispersal can average 100 m/year (1 km/decade).


"Thuiller et al consider that trees cannot move faster than 5 km/decade and present-day migration rates of 83-126 and 50-81 m/year (approx. 1 km/decade) respectively have been observed for oaks (which are bird dispersed) and Southern pines (which are wind dispersed) whilst other sources suggest tree migration rates of 0.05 to 1 km/year. Thus we chose the highest value quoted, 5 km/decade, as our optimistic scenario for plant dispersal. We selected a value representative of the lower values, 0.1 km/year, as our realistic scenario. " explain the study authors.

However dispersal can be complicated by food sources not moving at the same rate, extra competition with existing species ranges and the prospect of no analog species communities developing as species move at differing rates. A study by US ecologist Mark Urban, published in January 2012, identified that predictions of the loss of animal and plant diversity due to climate change may be greatly underestimated as most predictions of the rate of extinctions don't take into account species competition and movement.

There are often large and substantial obstacles to hinder and prevent migration. Our cites and towns with criss-crossing patterns of railways and roads, our farms and mastery of agricultural land has cornered many species in isolated reserves and nature parks with remnant ecosystems often with no congruent ecosytem links to related ecosystem areas to allow species to migrate to follow their climate envelope. These species face a grim future of crossing hostile man-made landscapes to stay within their climate envelope or adapt to the changing climate in their island reserves with a high risk of extinction.

Table S1: Our dispersal scenarios showing dispersal rate assumptions for different taxonomic groups. Superscript numbers refer to the references used to determine the rates.
Dispersal Ability Plants Mammals Birds Reptiles Amphibians
No Dispersal 0 km/yr 0 km/yr 0 km/yr 0 km/yr 0 km/yr
Realistic 0.1 km/yr 1.5 km/yr 1.5 km/yr 0.1 km/yr 0.1 km/yr
Optimistic 0.5 km/yr 3 km/yr 3 km/yr 0.5 km/yr 0.5 km/yr


Human population growth is also continuing to drive land use changes altering ecosystems and driving species to extinction. Kevin J Gaston in a 2005 paper on Biodiversity and extinction: species and people (PDF) detailed that "The most important agent of change in the spatial patterns of much of biodiversity at present is ultimately the size, growth and resource demands of the human population...giving rise to levels of global species extinction largely unprecedented outside periods of mass extinction."

The study was based upon the A1B emissions scenario where temperatures would be constrained to 2 degrees C through mitigation action. But global climate mitigation has been limited with emissions increasing on a business as usual trajectory associated with the Representative Concentration Pathway (RCP) 8.5 in which global temperatures exceed 4°C by 2100. The report done by the Potsdam Institute for Climate Impact Research for the World Bank warned this would bring severe impacts to biodiversity, agriculture and human infrastructure and civilisation. Constraining emissions may therefore bring substantial benefits for maintaining biodiversity, allowing more time for species adaptation.

"Since the completion of this study it has become evident that emissions are in fact increasing faster than our baseline scenario, and that it is therefore conceivable that a business as usual scenario that does not consider climate change mitigation could have significantly higher emissions than the A1B scenario, matching for example, the radiative forcing trajectory associated with the new Representative Concentration Pathway (RCP) 8.5 in which global temperatures exceed 4°C by 2100. Our comparison between climate policies including mitigation with those containing no mitigation may therefore underestimate the potential benefits." the authors conclude in the supplementary information.

Here is the study abstract in full:

Climate change is expected to have significant influences on terrestrial biodiversity at all system levels, including species-level reductions in range size and abundance, especially amongst endemic species. However, little is known about how mitigation of greenhouse gas emissions could reduce biodiversity impacts, particularly amongst common and widespread species. Our global analysis of future climatic range change of common and widespread species shows that without mitigation, 57±6% of plants and 34±7% of animals are likely to lose >=50% of their present climatic range by the 2080s. With mitigation, however, losses are reduced by 60% if emissions peak in 2016 or 40% if emissions peak in 2030. Thus, our analyses indicate that without mitigation, large range contractions can be expected even amongst common and widespread species, amounting to a substantial global reduction in biodiversity and ecosystem services by the end of this century. Prompt and stringent mitigation, on the other hand, could substantially reduce range losses and buy up to four decades for climate change adaptation.

Sources:

is a citizen journalist from Melbourne who has been writing on Climate Change issues and protests including Rising Sea Level, Ocean acidification, Environmental and social Impacts since 2004.