Climate change impacts will require major but very uncertain transformations of global agriculture systems by mid-century, according to new research from the International Institute for Applied Systems Analysis in Vienna, Austria.

Climate change will require major transformations in agricultural systems, including increased irrigation and shifts in production from one region to another, according to the new study, published in the journal Environmental Research Letters. However without careful planning for uncertain climate impacts, the chances of getting adaptation wrong are high, according to experts.

The new study by IIASA researchers provides 'a global scenario analysis', looking at nine different potential climate scenarios, 18 crop types and 4 crop management systems, as well as the interactions between crop production, consumption, prices, and trade.

The researchers paid particular attention to adaptation strategies that require significant investment and are not easily reversible, such as building new water management infrastructure for irrigation, or increasing (or possibly decreasing) production in different regions.

Commenting on the researchers' areas of scrutiny, study leader David Leclère said, "There is a lot of uncertainty in how climate change will impact agriculture, and what adaptations will be needed. Our new study is the first to examine at a global scale whether the adaptations required from agricultural systems are in the transformational range, and whether these transformations are robust across plausible scenarios.

"By looking at where, when, why, and which transformations are required, but also in how many scenarios, it lays the groundwork for countries to better plan for the impacts of climate change."

In line with earlier research findings, the study suggests that the impacts on crop yields of changes in climate (such as increased temperature, changing precipitation levels, along with the increased CO2 atmospheric concentration – which could even fertilise certain crops), could lead to anywhere between an 18% decline in global production from cropland by calorie, to as much as a 3% increase by 2050. The IIASA team reiterated that there is a high degree of uncertainty where climate change is concerned, and said projected impacts vary widely from region to region, crop to crop and for different management systems.

In October, scientists reporting in a special edition of the Bulletin of the American Meteorological Society revealed that extreme weather events – which can be linked conclusively to human activity – are already having measurable effects in several global regions, notably Australia where prolonged heat and drought have affected agriculture in the South and East of the country.

Dr Markus Donat, one of the scientists who contributed work to the Bulletin, said, "When it comes to what helped cause our hottest year on record, human-caused climate change is no longer a prime suspect, it is the guilty party. Too often we talk about climate change impacts as if they are far in the future. This research shows they are here, now."

What changes will be needed?

Meanwhile the IIASA researchers used a special computer model (which includes land use, trade, consumption, water resources, and other factors in its calculations) to identify what adaptation measures and changes are necessary for global agricultural systems.

"Our results confirm that the choice of the climate model used for estimating changes in climate largely shapes adaptations such as moving production from one region to another. But it also shows the importance of how regions are interconnected through trade: for example, in Latin America, where yields are projected to decrease in all scenarios, cropland could increase in some scenarios due to increased net exports to North America. In Europe, where yields are expected to increase due to climate change, cultivated land could decrease depending on the scenario, due to limited export opportunities," said Leclère, explaining the complexity of examining future scenarios.

The IIASA researcher said that a comprehensive analysis that includes climate impacts, policy decisions and market factors is nevertheless essential to understand changes and plan for the developments that will be needed in the near future.

Leclère's study also reiterates the importance of limited water resources for future food security in a changing climate, showing that in a large part of the world, increases in irrigation larger than 25% may be required. However, these increases may be unsuitable for certain regions as early as 2030, depending on the climate change scenario, according to Leclère, who added, "We have known for a long time that changes to rainfall are a major uncertainty. This study shows how important irrigation will be as an adaptive measure, but also how sensitive it is to different climate scenarios."

Overall, the study finds, almost no adaptation strategies will be 'robust' across all of the nine possible eventualities. "People often say that agriculture is adaptable--that throughout history, agricultural systems have shown a large capacity to evolve," explained Leclère, "It's important to examine this assertion further, as achieving a climate-ready global food system will definitely be challenged by the uncertainties at stake."

Michael Obersteiner, the study's co-author added, "After decades of global research efforts, scientists are only starting to understand the implications of climate change for the future global food system. We need to explore new and uncertainty-proof paradigms for long-term decision-making, and we also need a much better understanding of how to manage crucial resources such as water, which may become dramatically scarcer much earlier than previously thought."

Fellow IIASA researcher Petr Havlík said that the major challenge is looking at complex potential scenarios and establishing systems that will work, despite the huge uncertainties. Havlik said, "Our models show that there is an effective global adaptation strategy to any single climate change scenario. The challenge we face is to find the strategy which fits a hundred scenarios at the same time."