As global food demand rises, climate change is hitting our staple crops



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Farmers face falling crop yields and growing food demand.
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Andrew Borrell, The University of Queensland

Climate change and extreme weather events are already impacting our food, from meat and vegetables, right through to wine. In our series on the Climate and Food, we’re looking at what this means for the food chain. The Conversation


While increases in population and wealth will lift global demand for food by up to 70% by 2050, agriculture is already feeling the effects of climate change. This is expected to continue in coming decades.

Scientists and farmers will need to act on multiple fronts to counter falling crop yields and feed more people. As with previous agricultural revolutions, we need a new set of plant characteristics to meet the challenge.

When it comes to the staple crops – wheat, rice, maize, soybean, barley and sorghum – research has found changes in rainfall and temperature explain about 30% of the yearly variation in agricultural yields. All six crops responded negatively to increasing temperatures – most likely associated with increases in crop development rates and water stress. In particular, wheat, maize and barley show a negative response to increased temperatures. But, overall, rainfall trends had only minor effects on crop yields in these studies.

Since 1950, average global temperatures have risen by roughly 0.13°C per decade. An even faster rate of roughly 0.2°C of warming per decade is expected over the next few decades.

As temperatures rise, rainfall patterns change. Increased heat also leads to greater evaporation and surface drying, which further intensifies and prolongs droughts.

A warmer atmosphere can also hold more water – about 7% more water vapour for every 1°C increase in temperature. This ultimately results in storms with more intense rainfall. A review of rainfall patterns shows changes in the amount of rainfall everywhere.

Maize yields are predicted to decline with climate change.
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Falling yields

Crop yields around Australia have been hard hit by recent weather. Last year, for instance, the outlook for mungbeans was excellent. But the hot, dry weather has hurt growers. The extreme conditions have reduced average yields from an expected 1-1.5 tonnes per hectare to just 0.1-0.5 tonnes per hectare.

Sorghum and cotton crops fared little better, due to depleted soil water, lack of in-crop rainfall, and extreme heat. Fruit and vegetables, from strawberries to lettuce, were also hit hard.

But the story is larger than this. Globally, production of maize and wheat between 1980 and 2008 was 3.8% and 5.5% below what we would have expected without temperature increases. One model, which combines historical crop production and weather data, projects significant reductions in production of several key African crops. For maize, the predicted decline is as much as 22% by 2050.

Feeding more people in these changing conditions is the challenge before us. It will require crops that are highly adapted to dry and hot environments. The so-called “Green Revolution” of the 1960s and 1970s created plants with short stature and enhanced responsiveness to nitrogen fertilizer.

Now, a new set of plant characteristics is needed to further increase crop yield, by making plants resilient to the challenges of a water-scarce planet.

Developing resilient crops for a highly variable climate

Resilient crops will require significant research and action on multiple fronts – to create adaptation to drought and waterlogging, and tolerance to cold, heat and salinity. Whatever we do, we also need to factor in that agriculture contributes significantly to greenhouse gas emissions (GHGs).

Scientists are meeting this challenge by creating a framework for adapting to climate change. We are identifying favourable combinations of crop varieties (genotypes) and management practices (agronomy) to work together in a complex system.

We can mitigate the effects of some climate variations with good management practices. For example, to tackle drought, we can alter planting dates, fertilizer, irrigation, row spacing, population and cropping systems.

Genotypic solutions can bolster this approach. The challenge is to identify favourable combinations of genotypes (G) and management (M) practices in a variable environment (E). Understanding the interaction between genotypes, management and the environment (GxMxE) is critical to improving grain yield under hot and dry conditions.

Genetic and management solutions can be used to develop climate-resilient crops for highly variable environments in Australia and globally. Sorghum is a great example. It is the dietary staple for over 500 million people in more than 30 countries, making it the world’s fifth-most-important crop for human consumption after rice, wheat, maize and potatoes.

‘Stay-green’ in sorghum is an example of a genetic solution to drought that has been deployed in Australia, India and sub-Saharan Africa. Crops with stay-green maintain greener stems and leaves during drought, resulting in increased stem strength, grain size and yield. This genetic solution can be combined with a management solution (e.g. reduced plant population) to optimise production and food security in highly variable and water-limited environments.

Other projects in India have found that alternate wetting and drying (AWD) irrigation in rice, compared with normal flooded production, can reduce water use by about 32%. And, by maintaining an aerobic environment in the soil, it reduces methane emissions five-fold.

Climate change, water, agriculture and food security form a critical nexus for the 21st century. We need to create and implement practices that will increase yields, while overcoming changing conditions and limiting the emissions from the agricultural sector. There is no room for complacency here.

Andrew Borrell, Associate Professor, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland; Centre Leader, Hermitage Research Facility; College of Experts, Global Change Institute, The University of Queensland

This article was originally published on The Conversation. Read the original article.

Australia’s carbon emissions and electricity demand are growing: here’s why


Hugh Saddler, Australian National University

Australia’s greenhouse gas emissions are on the rise. Electricity emissions, which make up about a third of the total, rose 2.7% in the year to March 2016.

Australia’s emissions reached their peak in 2008-2009. Since then total emissions have barely changed, but the proportion of emissions from electricity fell, largely due to falling demand and less electricity produced by coal. But over the last year demand grew by 2.5%, nearly all of this supplied by coal.

In 2015 I wrote about concerns that Australia’s electricity demand and emissions would start increasing again. This has now come true. So what’s driving the trend?

Why did demand fall?

To understand this trend we need to look at data from Australia’s National Electricity Market (NEM), which accounts for just under 90% of total Australian electricity generation. While the NEM doesn’t include Western Australia or the Northern Territory, it has much better publicly available data.

The chart below shows electricity generation from June 2009 to March 2016.


Hugh Saddler, Author provided

The most important things to note are that, until February 2015, overall generation fell and the amount of electricity supplied by coal also fell. These two trends are closely related.

In June 2009, coal was supplying 84% of electricity, while 7% came from renewables (mainly hydro and wind) and 9% from gas.

Because renewables have near-zero short-run marginal costs (because they don’t have to pay for fuel) they will nearly always be able to outcompete coal and gas. This will be particularly so when demand for electricity falls.

Since June 2009 coal has been squeezed out by falling demand and a growing supply of renewables and gas. Until February 2015, total demand fell 8%, gas supply rose 43%, renewable supply grew 55% and coal supply fell 18%.

A dangerous trend

Since February 2015, however, these trends have reversed, which is very bad news for Australia’s emissions. Demand grew 2.5% and, combined with falling electricity supply from gas and renewables, coal picked up the slack, driving emissions 2.7% higher.

Gas generation is being forced out of the market, as wholesale prices throughout eastern Australia have risen to levels set by the three new liquefied natural gas (LNG) plants in Queensland.

Renewable generation, mainly hydro, increased briefly thanks to the carbon price, further squeezing out coal, but this is of course now gone.

Growth in other renewable generation (mainly wind) has stalled because of the near-total freeze in new investment under the reduced large-scale Renewable Energy Target (LRET) precipitated by the Abbott government.

Why is demand increasing?

To understand why demand is increasing we can look at the three major consumer groups – industry, business and households – as you can see in the figure below.

Victoria is excluded because differences in the timing of industry reporting to the AER mean that the most recent data are not available. Exclusion of Victoria does not change the overall picture, as it has shown the same trends as the other NEM regions.
Hugh Saddler using data from AER and AEMO, Author provided

After growing until 2012, industry demand fell sharply because of closures of several major establishments, most notably aluminium smelters in New South Wales and Victoria.

Since 2015 very rapid growth has occurred in Queensland, driven by the coal seam gas industry. Extraction of coal seam gas requires the use of enormous numbers of pumps, compressors and related equipment, to first extract the gas from underground and then to compress it for pipeline transport to the LNG plants at Gladstone.

Initially, the industry used gas engines to power this equipment, but then realised that electric motor drive would cost less. The government-owned Queensland electricity transmission business, Powerlink Queensland, is making major investments (paid for by the gas producers) in new transmission lines and substations to meet this new demand.

By the end of 2017-18, electricity demand could increase by 20% in Queensland and by 5% for Australia overall. All of this demand, at least initially, will be supplied by coal-fired power stations, increasing Australia’s total emissions by about 8 million tonnes, or roughly 1.5%.

As a side note, the LNG plants in Queensland will not themselves use electricity from the grid, but will use about 120 petajoules of gas each by 2017-18, adding another 6 million tonnes to national greenhouse gas emissions.

Household and business demand

Household demand fell since 2010 due to energy standards on appliances, increasing electricity prices and a one-off behavioural response due to unprecedented political attention to electricity costs thanks to climate policy.

Now electricity prices have stabilised or are falling and attract much less attention. Moreover, fewer appliance energy standards are being introduced, slowing the decrease in demand.

The result is that average electricity consumption per household, which fell by 17% between 2010 and 2014, has stabilised. In the absence of stronger energy efficiency policies and programs, residential electricity consumption can be expected to grow in line with population.

Business is the largest of the three consumer groups. Electricity demand fell slightly between 2010 and 2014. This is because electricity intensity, the amount of electricity needed to produce economic value, fell 3% each year; that is, slightly faster than the economy grew.

It now appears, however, that in the past year the fall in electricity intensity has almost ceased, so that total consumption has increased in line with economic growth.

A challenge for energy and climate policy

In December 2015 the federal and state governments announced the National Energy Productivity Plan to increase energy productivity 40% by 2030. This is part of the plan to meet Australia’s 2030 climate target.

Energy productivity is the economic value produced per unit of energy. The 40% goal is equivalent to a reduction of just under 30% in the energy intensity of the economy.

In the case of electricity, had the trend of the period 2010 to 2014 continued, this would have been achieved quite easily. It now appears to be a much more challenging goal, requiring the urgent introduction of a range of new energy efficiency policies and programs.


CORRECTION: The lead image has been corrected. It previously incorrectly showed aluminium works at Gladstone, Queensland.

The Conversation

Hugh Saddler, Honorary Associate Professor, Centre for Climate Economics and Policy, Australian National University

This article was originally published on The Conversation. Read the original article.