1. Jeff Obbard review of 2017 The Heat Is (Still) On:  2017 The Year in Perspective

By Prof. Jeff Obbard.

The temperature records for 2017 are in. According to the National Aeronautical and Space Administration (NASA), 2017 was the second warmest year on record. When compared to temperatures in a ‘pre-industrial’ times, 2017 was 1.17°C warmer than the average global temperature for the years between 1880 and 1920.  The warmest year to date was 2016, where the average global temperature was 1.24^oC warmer than the 1880-1920 base period.

So, is this good news, perhaps a sign that the pace of global warming has slowed down?  Sadly not, because there is a critical difference between the 2016 and 2017 temperatures. In 2016, temperatures were boosted by a prevailing tropical El-Niño event which naturally warmed the climate, but this had mostly dissipated by the start of 2017.  Therefore, 2017 was the warmest non-El Nino year on record, beating the previous non-El-Nino year in 2015 – mostly due to the unusually warm temperatures recorded in the Earth’s polar regions.

Recently, the United Nations World Meteorological Organization (WMO) noted that paying attention to the long-term global temperature trend is more relevant than variations between individual years.  That long term trend is a firmly upward one: 17 of the 18 warmest years on record have all occurred in this century, where the degree of warming over the past three years has been exceptional.  Arctic warming has become so pronounced that the WMO believes that this is likely to have profound and long-lasting repercussions on sea levels and weather patterns around the world.

Certainly, global temperatures in 2017 continued to remain above the recent trend line of increasing global temperatures over the last several decades (see Fig. 1). It is possible that this temperature excursion is not only due to the increased climate forcing due to the overburden of greenhouse gases in the atmosphere, but also feedbacks in the climate system that accelerate warming. Such feedbacks are associated with changes in the reflectivity of the Earth’s surface (for example, the loss of reflective ice in the Arctic) and/or the release of greenhouse gases from natural carbon stores in the Earth (for example, the loss of methane and carbon dioxide from melting Arctic permafrost).

This observation is supported by the paradox of accelerating levels of greenhouse gases in the atmosphere despite a near-plateau in anthropogenic (i.e. human-derived) carbon emissions in the last 3-4 years.  In its Fifth Assessment Report, the IPCC stated that evidence for a warming of the Earth’s atmosphere and ocean is now unequivocal (i.e. a 99% certainty), and that it is extremely likely (i.e. a 95-100% certainty) that human influence has been the dominant cause of observed global warming since 1950, adding that observed warming is unprecedented in the Earth’s historical climate record. Indeed, since 1990 alone, it is estimated that radiative forcing due to greenhouse gases emissions has increased by 40% and this, in turn, has enhanced the risk of crossing climate tipping points. According to the Intergovernmental Panel on Climate Change (IPCC), once tipping pints are crossed, then climate change can become abrupt and irreversible.

The 2017 global temperature data underscores the importance of meeting the targets of the Paris Climate Agreement where the world pledged to keep global temperature rise to well-below 2^oC, with the aspirational target of no more than 1.5^oC. The lower target is favoured by developing nations that are the least responsible, but the most vulnerable, to climate change impacts associated with anthropogenic carbon emissions.

In a recently leaked draft of a United Nations report on the prospects for meeting the more ambitious 1.5^oC target, it is stated that here is a “very high risk” that the target is likely to be exceeded by the 2040s under current greenhouse gas emission trends. According to the report, only a dramatic and unprecedented shift away from fossil fuels will enable the world to limit warming to no more than 1.5^oC above pre-industrial times. Drastic reforms of industrial and agricultural practices will also be needed to avoid more heatwaves, droughts and floods, as well as the risks of mass migration of people and even conflicts triggered by a warming climate. Indeed, at current greenhouse gas emission rates, a breach of the 1.5^oC target may only be 12 years away and may even require active removal of carbon dioxide from the atmosphere – something dependent on so-called ‘negative emission technologies’ which are still nascent and prohibitively expensive. The UN prediction also excludes the risk of crossing climate tipping points that would trigger a surge in greenhouse gas emissions from natural sources.

Under the Paris Climate agreement nearly 200 nations pledged to curb greenhouse gas emissions and so prevent what the United Nations defined back in 1992 as “dangerous anthropogenic interference with the climate system”. According to the draft UN report, renewable energies such as solar and wind power must become the dominant source of energy by 2050 in-order to achieve the 1.5^oC goal, where coal should be phased out quickly.

The United States President Donald Trump, has expressed doubt that climate change is man-made, and has instead decided to focus on promoting US fossil fuel sources, including coal. In June last year, he announced that the US will withdraw from the Paris Climate Agreement. Interestingly, and perhaps encouragingly, a new report by the Bloomberg New Energy Finance group indicates that global investment in renewable energy in 2017 rose to a record US$330 billion. According to Bloomberg, the cost of solar energy continued to decline sharply in 2017, and this played a major role in the 18 per cent rise in solar investment of over US$160 billion in 2017. Wind power and other energy-smart technologies, such as smart meters and batteries also received a big investment boost in 2017, where China was the largest investor in clean energy technologies in 2017 at US$130 billion, followed by the US at US$56 billion. It may be that these sorts of investment figures that finally catch the attention of Mr Trump and bring the US could back to the Paris Agreement. Indeed, the message is clear: moving the world toward a low-carbon future has become as much of an economic imperative as an environmental one.  Mr Trump, please take note!