There is now a broad international consensus that climate change is a serious problem and one that requires stronger responses from many governments. The global focus now needs to move from convincing the unconvinced minority to finding practical solutions while the planet still has time. The UNDP Oxford University Peoples’ Climate Poll (2021) and earlier international polls confirm that majorities in virtually all countries surveyed agree that climate change is real and is caused by human activities. Australia and New Zealand have climate majorities in the 72–80% range. So, what strategies do our countries have to adopt to achieve the aim of zero carbon by 2050? The first step is to review what new solutions are emerging internationally; then we need to evaluate which of these are feasible candidates for climate remediation in the Australasian region.
Natural climate solutions
One strategy that is gaining momentum relates to natural climate solutions. Natural climate solutions involve conservation, restoration and improved land management actions that increase carbon storage or avoid greenhouse emissions in landscapes and wetlands. Natural climate solutions are being promoted by the World Economic Forum and other organisations. A recent report in Proceedings of the National Academy of Sciences indicates that this strategy including mitigation pathways could contribute up to 37% of carbon dioxide reduction and hence play a significant role in enabling the planet to achieve the <2°C warming objective. This is not a new strategy, and it includes massive reforestation projects such as the iconic Great Green Wall crossing Africa along the southern margins of the Sahara. This extraordinary project led by the African Union, will deliver both climate and food benefits to impoverished populations in several African countries that depend largely on natural food sources. The Great Green Wall has had its difficulties, but now appears to be approaching a successful conclusion. If the Great Green Wall does succeed, it should inspire other similar and smaller natural climate solutions projects elsewhere in the world.
Improved solar and wind technologies
A second strategy is to further develop, refine and scale up existing solar and wind energy systems. The World Economic Forum has recently reported on some of these developments. The long-term trend of increasing efficiency in solar panels is expected to continue, given the development of hybrid panels that combine photovoltaic cells and thermoelectric cooling modules to improve system efficiency. Building-integrated photovoltaics are a new generation of solar films that are integrated into building envelopes, thereby achieving greater efficiency and improved aesthetics by avoiding the rather functional appearance of conventional panels. Floatovoltaics are another larger scale development that deploy solar panels on bodies of water. Floatovoltaics are simpler to install than on land, and the natural cooling effect of water can significantly increase efficiency and output. The world’s largest floatovoltaic facility in the Sirindhorn Reservoir 660 kilometres from Bangkok involves 145 000 solar panels that harness solar energy during the day and three turbines that extract the accumulated energy by night.
A related development involves floating islands of wind turbines that are expected to alter the global energy landscape. The global wind energy market has quadrupled in size over the past 10 years. For California, in particular, floating offshore wind farms could be the key to the state achieving 100% renewable electricity by 2045. The Gansu Wind farm (pictured) in western China will be one of the largest wind farms when completed, with 7000 turbines and 20 GW output. This is enough to power a small country. The largest offshore wind farm at present is Hornsea 1 (UK) with 174 turbines that generate 1218 MW output. Significantly, Statoil – a major oil company – is now developing oceanic wind farms. This is an example of a growing trend in which large oil and gas companies are developing major projects in renewable energy.
New, safer nuclear power
A third strategy involves new, safer sources of nuclear energy technology. Nuclear energy generally does not contribute to atmospheric greenhouse gas emissions such as carbon dioxide, methane, nitrous oxide and chlorofluorocarbons. Bill Gates argues that we will not be able to achieve a sustainable climate solely by switching from fossil fuels to solar, wind, hydro, green hydrogen etc. To fill the gap, Gates advocates the increased deployment of new nuclear technologies that do not generate greenhouse gases and are safer than large nuclear power sources. An Our World in Data report (sources include the journals Nature and Lancet) confirms that coal, natural gas and biomass all involve many more fatalities than nuclear. Doubling of large nuclear power plants are planned for the fastest growing emissions country, China, as it seeks to replace coal by nuclear energy over the next 10 years as a step towards zero carbon by 2060.
These new nuclear technologies include preconstructed small modular reactors, which could power a small town, an airport or a hospital. Small modular reactors are being developed by NuScale, Westinghouse and Rolls Royce and seem very likely to play a role in major northern hemisphere countries (USA, Canada, UK, EU). The smaller scale of small modular reactors brings disadvantages of scale and cost compared with large conventional reactors.
Another option under development is the thorium reactor being developed in Norway by Thor Energy. A prototype thorium reactor has been developed in China and another exists in India. Thorium reactors have advantages over uranium reactors in that they can be closed down quickly, generate much less nuclear waste and cannot be used to make weapons. The thorium mineral monazite is abundant in many countries, including India and Australia. India, with its increasing carbon emissions associated with coal deployed for economic development, has only recently set itself an extrapolated zero carbon target (2070). Thorium reactors may in the future provide India with a silver bullet to achieve zero carbon on a more realistic time frame.
Fusion reactor technology has been in development for decades. Nuclear fusion simulates the energy-generation processes in the Sun. If fusion energy can be recreated on Earth, it holds the potential of virtually unlimited supplies of low-carbon, low nuclear-radiation energy. The next-generation ITER fusion reactor in France (using heavy isotopes of hydrogen) is being developed by the EUROfusion Consortium, which involves 5000 science and engineering experts. Reports suggest that the necessary scale-up development of fusion reactors will take longer than the generic zero carbon deadline of 2050. On the other hand, the recent emergence of 25 start-up companies in fusion technology is expected to accelerate this urgent and transformational development.
In both Australia and New Zealand, there has been an understandable reluctance to embrace conventional nuclear energy. In the case of New Zealand, which already has a high proportion of its energy from sustainable sources, it is difficult to see a conventional large-scale nuclear power station playing a significant future role. Indeed, a single conventional nuclear power station would oversupply the national grid, which in turn would create contingency issues. However, the remaining New Zealand coal power station at Huntly, which is due for replacement in 2025, acts as a safety net when hydro sources are depleted by drought. Huntly might conceivably be replaced by a few small modular reactors.
Sequestration of atmospheric carbon dioxide
A fourth strategy involves the removal of existing carbon dioxide from the atmosphere. A facility in Iceland is operational and effectively is a proof of concept on a small scale. This facility recovers 4000 tonnes per year of carbon dioxide that is converted into carbonate minerals, which are then buried. The problem with this technology is that its scale is dwarfed by the massive rate of increasing global carbon emissions (52 billion tonnes per year). It would clearly be simpler, much less expensive and more sensible to simply reduce our current emissions. However, the Iceland facility does constitute a small-scale proof of concept and the decision by Exxon to establish a $100 billion carbon recapture hub will hopefully provide a more demanding and better scaled test of this technology.
A final more radical strategy involves injecting sulfate particles into the upper atmosphere to reflect excess solar energy back into space. This concept was based on the natural atmospheric cooling caused by volcanic particles that was observed during the Pinatubo volcanic eruption in 1991. This natural process was quantified by Paul Crutzen, who was awarded the Nobel Prize in Chemistry in 1995, and his analysis could provide guidelines for the injection of the particles into the atmosphere. An in-depth and more recent Nature Education review indicates that large-scale temporal and spatial variability makes this strategy more complex than originally thought.
Conclusion: the global state of play
The global expectation of achieving zero carbon status can be summarised in the following 10 aims and probabilities. The probabilities of success reflect the author’s judgement: certain, feasible or uncertain.
- The global population will plateau by 2100 at 11 billion and populations in some high-emitting countries (China and India) will decrease by 2050 and by 2100 respectively (certain).
- Natural remediation strategies will provide a maximum of 37% of remediation (feasible but not certain).
- Large-scale floating wind farms and floatovoltaics will become more widely utilised (certain).
- China will replace coal by large nuclear reactors within 10–20 years (almost certain).
- India will develop and implement thorium reactors to replace coal (uncertain).
- The USA and EU will continue to reduce emissions by adopting renewable technologies, including small nuclear energy (almost certain).
- The electric transportation revolution (cars, planes, ships etc.) already underway will continue to conclusion (certain by 2050).
- About 130 out of 198 countries have adopted zero carbon targets so far but an even greater global majority is needed (promising but not certain).
- Only 9.8% of 965 cities’ climate strategies evaluated by CDP in 2021 were ranked A and a higher level of commitment is needed (uncertain).
- A fifth of the world’s largest companies have committed to a net zero target (Forbes, 2021) and this number is expected to grow rapidly, driven by international consumer pressure (certain).
There are significant grounds for optimism in the above global score card. However, the increasing drive for renewables and other strategies will have to accelerate over the next few decades if we are to achieve our zero carbon targets in 2050.