http://iprc.soest.hawaii.edu/news/press_releases/2012/monsoon_climate_change.pdf
http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1495.html
‘South Asian monsoon variations hard to fathom’
T.V. Padma
4 July 2012 | EN
Monsoon changes due to global warming still difficult to decipher, says a review
Flickr/fbloeink
[NEW DELHI] Understanding how the South Asian monsoon will change in response to global warming and resolving the uncertainties in projected changes are ‘demanding tasks’ for climate science, a review says.
Current state-of-the-art general circulation models have difficulty simulating the regional distribution of monsoon rainfall, the 24 June review in Nature Climate Change says.
The vagaries of the monsoon on short- and long-term timescales impact the lives of more than a billion people in South Asia who depend on rainfall for agriculture, power generation, industrial development and basic human needs.
Authors, Andrew Turner, National Centre for Atmospheric Science-Climate, University of Reading, and Harisubramaniam Annamalai, International Pacific Research Centre, School of Ocean and Earth Science, University of Hawaii, say variations in the amount of monsoon rains in different years are low (10 per cent of the total summer rainfall).
But, variations within each season, over timescales of a few days or weeks, often have large impacts on agriculture or water supply.
“Perhaps the single biggest scientific challenge is in understanding monsoon variability at intra-seasonal timescales (several weeks), the so-called active and break events in the monsoon, and how they will change in the future,” Turner told SciDev.Net.
They “are poorly understood and difficult to predict,” he said.
The review also describes observed changes to monsoon rainfall over the second half of the 20th century such as an unprecedented rise in greenhouse gases and aerosols (tiny suspended particles in the air, such as sulphates from industry or soot from cook stoves).
Models linking monsoon responses to global warming suggest a rise in monsoon rainfall, but there is a high degree of uncertainty in these projections. Observations from data sets from most areas indicate a declining trend or no change in monsoons, contrary to the projected rise.
Turner explained that there could be reasons for the mismatch between observed and projected monsoon rainfall trends.
Increases in aerosols from pollution since the 1950s may be absorbing the sun’s radiation reaching the earth, impacting temperature differences over land and sea and, in turn, the monsoon.
Other possible factors include the effects of land-use change (the impact of the green revolution and massive expansion in irrigation in northern India, for example), or natural decadal variations in the rainfall, he said.
The review also highlights the need for reprocessing data, consistent data sets and a better understanding of the physics and complex dynamics behind monsoon circulation.
Co-author Annamalai told SciDev.Net that “as far as the Indian monsoon rainfall data goes, it is mostly about data processing techniques.”
When data from observing stations is projected or mapped into regular latitude and longitude grid points, different research groups employ different techniques, he explained.
“It is unclear how many ‘true observed station rainfall data’ go into each and every grid,” Annamalai said.
If we were to go by Oxfam’s policy document – Growing Better Future or ActionAid’s – ‘On the Brink or the ICRIER-Gene Campaign Policy Paper 16: ‘Impact of Climate Agriculture & Food Security’, all based on the so called Climate Smart Agriculture (CSA) paradigm, we can’t be faulted to be left with an impression that CSA is a magic wand wherein all solutions are known and further these NGOs have actually the in situ capability to translate these into action!
But wait a minute. What did this new “Nature Climate Change” study actually find? Let’s read their opening sentence once again:
“Understanding how the South Asian monsoon will change in response to global warming and resolving the uncertainties in projected changes are ‘demanding tasks’ for climate science.”
Translated: Present “climate science” have no clue of monsoon behaviour” because uncertainties are so huge that makes its prediction highly challenging!
If this being the case, how climate smart can these NGO agricultural solutions be?
Read more: http://devconsultancygroup.blogspot.in/2012/07/new-study-exposes-ngos-climate-smart.html
The above comment and the linked article penned by Rajan Alexander paints an extremely distorted picture of our Nature Climate Change review article (Climate Change and the South Asian Monsoon, Nature Climate Change, doi:10.1038/nclimate1495), blatantly misrepresents the science and implies a viewpoint that we have not presented and do not support.
The comment states that “climate science has no clue of monsoon behaviour”- this is patently untrue. The scientific evidence (from basic theory and from a large number of climate modelling experiments) clearly suggests that as a whole monsoon rainfall will increase somewhat in the future and due to the expected increase in atmospheric moisture there is some evidence that rain will fall in heavier bursts. Such changes point to increased risk of flooding.
However, there is a considerable range in the magnitude of the projected increase in rainfall and climate models do not agree on the local detail of how rainfall might change within South Asia. It is often such local detail that is most relevant when planning how to adapt to climate change, e.g., in the agriculture and infrastructure sectors. These disagreements between climate models are due to inaccuracies in the way current models represent some of the small scale physical processes, in part related to a lack of quality observations to constrain the models. As we argue in the Nature Climate Change paper, more reliable predictions of the future will be made when models can better simulate the local features of the monsoon and its variability on a range of timescales – from days to weeks and more. Such improvements are the focus of current monsoon research.
The linked article also perpetuates the old fallacy that one cannot predict the future climate many years ahead while there are still difficulties at making weather forecasts in the next days and weeks. The science of climate change is about “expected changes in the probability of occurrences of certain weather events” such as monsoon droughts and floods; as models improve in conjunction with our better understanding of the physical system, we are in the right direction to reduce the uncertainties in future projections – this is doable as climate community has demonstrated the tremendous accomplishment in the few decades in understanding and predicting, for example, El Niño events.
On the issue of Climate Smart Agriculture, of which we do not comment in our review, a cornerstone seems to be to enhance resilience and improve adaptation strategies. In our opinion, what better way to do this than improve the way that farmers adapt to variability in the current climate? The sort of floods or breaks in the monsoon that occur in recent and indeed all monsoon seasons have much larger impacts than the projected signals of future mean climate. The key to dealing with the changing climate will be to make sure that the adaptation strategies are themselves adaptable. In other words being able to adapt to current variations allows farmers and others to be able to make decisions even in the face of uncertainty in the climate models.
Dr Andy Turner, Dr H. Annamalai and Kathy Maskell