In the public domain, some of those accepting the science of man-made climate change question the feasibility of action based on the perceived economic cost of transitioning away from burning fossil fuels for energy and transport. This section canvasses technological and economic research which unambiguously show that mitigating future global heating through “decarbonization” is feasible and cost effective.
7.1. Transitional technologies
As discussed above, global heating depends on the Equilibrium Climate Sensitivity (ECS), which relates atmospheric CO2 concentration to atmospheric temperature. Surface and land and ocean temperatures have currently heated by approximately 1°C. If global CO2 emissions continue to grow according to current trends, temperatures will be between 3 and 5°C hotter by 2100 (Fig. 13), a level which will multiply the damage to ecosystems, health and economies. As outlined above, these impacts increase linearly or super-linearly with global heat, and conversely every strategy that effectively reduces future climate heating reduces these harms: Current international efforts aim to limit further heating to 0.5°C to contain these effects [report].
Figure 13: Model simulations estimates of global heating under different assumptions of GHG emission growth. Red: Heating with no change in current emission growth. Blue: Low emission growth: Orange: Hypothetical heating with GHG levels at year 2000 levels [report].
Global heating reflects the combined effect of increasing “greenhouse gases” (GHG) which includes CO2, methane and nitrous oxide. Stabilizing GHG concentrations, particularly CO2 (“decarbonization”) requires large-scale transformations in the way that we produce and consume energy, and how we use the land surface [report, site]. Several points are salient here:
1. Using existing and emerging technologies, there exist clear pathways to a substantial decarbonization across all sectors of production (Fig. 13) [paper, paper, paper]. These include transformations in energy, manufacturing, digital technologies, buildings, transport, food, as well as the development of novel “nature-based solutions” [report]. Almost all of this transformation can be achieved through up-scaling of existing technologies. One challenge includes carbon-neutral technologies for conversion of iron ore to steel (due to the high temperatures required for the blasting process). Addressing this challenge is the objective of several of the world’s largest manufacturers and is close-to-achievable [report].
Executing the transition presents challenging economies of scale and cannot be achieved without a strategically planned timeline, particularly in temperate climates with a high population density [site]. Australia’s low population density and high solar irradiance place it at highly strategic advantage for renewables: For example Australia’s entire electricity budget could be derived from solar panels alone covering less than 0.5% of the country [report]. In practice, the optimal mix of renewable energy in Australia will likely be a mix of solar, wind and geothermal [report].
2. To limit global heating to a further 0.5°C (total 1.5°C) requires immediate reductions in GHG emissions with a goal of zero net emissions by 2050. In particular, a decisive breakpoint (technically, a discontinuity in trend derivatives) is required to unlock global emissions from their current upward growth to an immediate, sustainable reducing trend [report]. Globally, GHG emissions are not showing evidence of this breakpoint, either in existing GHG emissions (which are at best slowing or otherwise continuing to grow), or in new emission policies. Australia, for example, continues to expand its major CO2 exports with new coal mines, such as the Carmichael mine, receiving billions of dollars in subsidies [site] for low quality, high ash coal [site] that is destined for regions that are particularly vulnerable to the impact of global heating, such as India.
3. Renewable energy (such as solar, wind, thermal, hydro) will play a crucial role in the decarbonization of society (Fig. 14) [paper] Energy production is a major source of global CO2 emissions, with flow-on effects to other sectors including transport, manufacturing, digital technologies and food storage.
Figure 14: Renewable energy and energy efficiency can provide over 90% of the reduction in energy-related CO2 emissions [report]: Projected annual energy-related CO2 emissions and reductions, 2015-2050 (Gt/yr) under a low emission growth scenario. Note the very sharp change in the use of CO2-based energy necessary in ~2020.
Both fossil-fuel and renewable power technologies carry life-cycle GHG emissions, mainly due to their construction and operation. However, when taking these factors into account, solar and wind emissions are less than 10% of fossil fuel-based power generation, even if these use advanced carbon capture and sequestration technologies [paper].
Transition to solar and wind also reduce air pollutants (“particulate matter”), bringing additional benefits for air quality in addition to heat mitigation [paper]. As a consequence of this benefit, decarbonization through renewable energy will avoid 0.5, 1.3 and 2.2 million premature deaths in 2030, 2050 and 2100 in addition to those avoided by unmitigated global heating [paper]. Because of the high premium that society places on avoiding death, the costs of changing electricity production to renewables will be substantially offset by reduced pollution-related mortality, especially in China and India [paper]. Under a low emission scenario, these savings exceed the costs of the associated decarbonization of the energy sector by 2050 [paper]. These savings are in addition to the benefits of mitigating global heating, but as they occur mainly locally, in the near term, and with high certainty, they contrast with the long-term distributed global benefits of slower heating, and therefore should further incentivize decarbonization at the national level (particularly in China and India) [paper].
The costs of renewables have plummeted exponentially over the last decade (Fig. 15). In 2018 alone, the global weighted-average cost of renewable electricity declined 26% for concentrated solar power (CSP), followed by bioenergy (14%), solar photovoltaic (PV) and onshore wind (both 13%), hydropower (12%), and geothermal and offshore wind (both 1%) [report]. As the cost of renewable energy continues to decline, certain renewable technologies (e.g. onshore wind and utility-scale solar), have now been cost-competitive with conventional coal and nuclear generation for several years, on a new-build basis [report]. These costs are cheapest for large-scale (wholesale) projects, followed by industrial and commercial, and most expensive when deployed residentially.
Figure 15: Exponential decreases in the levelized (whole cycle) costs of electricity (LCOE) from solar photovoltaic over the last decade [report] .
One criticism of solar and wind (but not hydro) has been their itinerant dependence on sun and wind. Concentrated solar power (CSP) generates electricity by using sunlight to heat a fluid. The heated fluid is then used to create steam that drives a turbine-generator set. Because CSP systems heat a fluid prior to generating electricity, thermal energy storage can be readily incorporated into the design of CSP plants, making them a source of “dispatchable” and 24-hour renewable power [report]. The cost of CST is expected to fall as it is further deployed around the world [report].
In sum, there are compelling economic and health benefits supporting the transition to renewable energy production, in addition to the mitigation of damage from global heating.
4. Decarbonizing the society does not require a reduction in total energy usage, or a contraction in economic growth (Fig. 14). On the contrary, the development and installation of renewable energy sources represent substantial economic and employment opportunities [site] – the private sector is already playing a pro-active role here [media]. To minimise economic disruption, decarbonization requires a planned, strategic and staged approach guided by achievable time posts [paper] . A crucial social component of this process is the implementation of a “just transition” whereby communities currently dependent on GHG-based industries (such as coal mining) are selectively targeted by government policies to incentivize their prioritized role in new non-CO2 economic opportunities [report]. Some of this could be achieved by re-directing current billion-dollar subsidies from CO2-based industries to carbon neutral industries. Independent strategic and advisory bodies have also requested greater policy certainty in this area [report], such as definitively resolving the prevailing government uncertainty over the construction of new coal-based power plants in Australia, financed “Soviet-style” by central government [media, media].
As reviewed above, fossil fuels are currently subsidized by about US$5trillion each year, with projected increases in accordance with further global heating [paper, report]. Redirected these subsidies is key to achieving a timely and cost effective decarbonization of the energy sector. For example, it has been estimated that a rapid decarbonization could be enabled by strategically redirecting US$15trillion of these fossil fuel subsidies to renewable sources, and investing a further similar amount [report]. In doing so, returns on these investments would be between US$65 and US$160 trillion. That is, for every $1 spent on energy transition, there would be a payoff of between $3 and $7, with a growth in employment and an increase in GDP of 5.3% over the current model [report]. Again, these savings are in addition to the implicit worth of preserving ecological systems and mitigated economic inequalities.
5. Carbon sinks play a major role in off-setting current GHG emissions and currently account for some recent slowing in the total GHG budget in the face of rising emissions. For example, in Australia, this (land use and forestry) sector is almost entirely responsible to improvements in the GHG emission budget [report], mainly through a decline in the harvesting of native forests, although partly through a maturation of plantation forests planted in the 1990s [report].
Global tree cover has increased slightly since the 1980s [paper]: Loss of tropical forests has been outpaced by increased woody growth in increasingly warmer regions of Northern Siberia and global sub-alpine mountainous regions. Although this is partly due to active reforestation policies in some regions (such as China), it is generally an inadvertent by-product of changes in human activity. For example, following the collapse of the Soviet Union in the 1980s, natural afforestation occurred on abandoned agricultural land in Eastern Europe [paper, paper]. The improved carbon balance in Australia’s land-use sector largely reflects the maturation of forest plantations planted in the 1990s, decreased carbon liberation from soil due to changes in agricultural tilling and decreased logging of native forests [report]. The first of these does not reflect contemporary carbon mitigation policies.
Restoration of tree cover at a global scale could substantially help mitigate climate change. It was recently shown that there is room for an extra 0.9 billion hectares of canopy cover, which could store 205 gigatonnes of carbon in areas that would naturally support woodlands and forests [paper]. Note that this is a ten-fold increase in the tree cover that has occurred since 1980 and would require substantial active government initiatives. Also, almost a quarter of this potential could be lost due to global warming by 2050. Moreover, as we have seen in Australia, global heating leads to faster drying and shorter windows for load-reduction through controlled burning [report]. In addition, fire suppression costs increase approximately 6-fold with high burn severity [paper], another consequence of global heating. Moreover, fire suppression is less effective in the presence of severe wind and heat events [paper] . Hence, although reforestation is an important component of GHG reduction, it requires careful strategic and economic planning. Habitat restoration to slow the decline of native species such as the Koala likely to represent only a very small total area of reforestation [report].
Offsetting GHs via reforestation can be seen as one of a broader range of “Negative emission technologies (NETs) which include industrial processes, such as carbon capture and sequestration, and direct air carbon capture and storage, plus ecosystem approaches including soil carbon sequestration biochar, blue carbon, enhanced weathering, and ocean fertilization [paper]. NETs are of relevance since they potentially allow accelerated decarbonization, particularly in light of inaction on other fronts (Fig. 16). However, although in active development, they are unlikely to be scale-able until well after 2030 [paper].
Figure 16. The potential role of NETs (blue) in decarbonization (paper).
7.2. So what is “climate alarmism”?
One often hears the term “climate alarmist” made against those who argue for immediate reduction of GHG emissions – indeed the words “alarmist” and “doomer” seem to have been weaponised on social media. The confusion likely arises because of the lag between current global CO2 levels and future global heating (e.g. see the heating associated with constant CO2 emissions; orange line in Fig.14). Hence the need for immediate effective action to limit future global heating and associated damage. Harmful, possibly irreversible, ecosystem changes will be locked in by 2030 if CO2 emissions continue to rise at current rates – well before those damages will be fully apparent. Under this scenario, mitigation to limit further heating to 0.5°C will not be feasible. It seems that the nuance between the urgency of effective action and the lag before further global heating is lost in the not-so-subtle world of social media.
Evidence reviewed above suggests that decarbonizing the economy by 2050 is cost effective, feasible, compatible with economic growth, and consistent with a mix of government policy and private sector investment. Put differently, taking this action is agnostic to the need for major structural economic or political change, although it does require that the technical advice of scientists is given greater weighting in decision making than is currently the case. Conversely, failure to effectively mitigate global heating will increase ecological and economical damage, placing greater duress on prevailing political systems and hence making those systems more vulnerable to social conflict and disruption [paper].
In light of these considerations, the term “alarmism” is arguably a more accurate description of arguments that suggest effective action on climate action is economically damaging or a disguised means of co-opting public goodwill for political change.
Next section: What is not causing climate change