New research anticipates that rising global temperatures will see southeastern counties take a hit on autumn grass growth over the coming decades, while growth in the northwest could see a boost.

The ClimAg project modelled the expected grass growth trends under two climate change scenarios after developing a modelling framework for predicting future fodder shortages.

The exercise was carried out under scenarios where global average temperatures rise 1.4°C or 2.0°C by the mid-21st century over the long-term temperature average, with these being the most likely and worst-case greenhouse gas emissions scenarios.

The work forecasts an almost doubling in the risk that the low rainfall levels seen between May and July 2018 will occur between 2041-2070, relative to their likelihood in the four decades prior to 2010.

More resilient

The researchers found that fodder production and pasture-based systems in the northwest of the country are likely to remain “more resilient than in the remainder of country under future climatic conditions”.

The decreases in forage production are anticipated to be most likely experienced during autumn in the southeast and during summer months in parts of the midwest.

Increased grass growth is generally anticipated by the model in the spring months, and the severity of summer declines in grass growth below the current average worsens in the higher-temperature global warming scenario.

Key to adequate fodder suppliers are autumn growth rates and an appropriate closing cover of grass, the project found.

It recommended that an early warning system be developed based off of these grass growth figures to allow farmers to take remedial action to prevent a fodder crisis setting in the following spring. Changes should be considered to grass and fodder management practices to account for these projections, it stated.

The project also developed a fodder crisis severity index, which combines climate change data with computer projections of grass growth.

The worst class of fodder crisis would be similar to those witnessed in 1947, 1976 and 2012/2013, the researchers said, occur over successive seasons of poor grass growth.