Do Two Climate Wrongs Make a Right?

As the planet approaches local and global exceedance of the 1.5°C stabilization target, damages from climate change, mostly due to extremes, are growing far faster than projected. While assessment models have largely estimated high costs of mitigation, the cost of green energy is dropping faster than projected. Climate policy has assumed that damage costs are manageable while decarbonization is expensive. Both these assumptions are wrong, potentially leading to a tipping point in human behavior: scientists need to explore options aligned with this emerging reality.

As the world feels the effects of climate change it is clear that analyses and models likely led to underestimation of the risks of increased extremes such as those now being experienced.Natural scientific caution and a desire not to extrapolate beyond what could be simulated played into the narrative of the 1990's that gave rise to the incorrect assumption that costs of climate change were manageable.Models are not intentionally biased toward catastrophic climate futures (Hausfather et al., 2020;Kemp et al., 2022), and are, at worst, realistic in projecting Abstract As the planet approaches local and global exceedance of the 1.5°C stabilization target, damages from climate change, mostly due to extremes, are growing far faster than projected.While assessment models have largely estimated high costs of mitigation, the cost of green energy is dropping faster than projected.Climate policy has assumed that damage costs are manageable while decarbonization is expensive.Both these assumptions are wrong, potentially leading to a tipping point in human behavior: scientists need to explore options aligned with this emerging reality.Natural ecosystems and the subsidy they provide to the human endeavor through carbon uptake also appear to be changing rapidly with climate, perhaps motivating more active management for resilience.In the 1990s, Woodwell and Mackenzie (1995) argued that "warming might speed the warming" with higher temperatures from anthropogenic greenhouse gases leading release of long-stored soil and biomass carbon.Recent studies suggest this transition to net emissions from tropical forests occurred in the Amazon not in the 2050s but in response to increasing drought frequency between 2010 and 2020 (Boulton et al., 2022;Gatti et al., 2021).

SCHIMEL AND MILLER
Climate also threatens agriculture more than expected in early assessments suggesting both the need for and the challenges of mitigation.World food security was long felt to be under only regional threat, but beginning with US assessments in the 2000s, evidence began to emerge of hard barriers to adaptation (Backlund et al., 2008).Gaupp et al. (2020) also showed that even regional drought impacts have global food security consequences and climate shocks can be destabilizing.
What of the cost and difficulty of decarbonization?In a recent analysis, Way et al. ( 2022) showed a pattern of consistently overestimated costs of decarbonization, comparing data to projections.They found that "IPCC conclusions thus appear to be based on an over-sampling of near worst-case scenarios regarding key green technology costs" and argue that for 40 years these overestimated costs have inhibited more aggressive action and that extrapolation of empirical data suggests the "green energy transition may be cheap".
The penetration of electric vehicles has exceeded expectations, and the cost of renewable energy, rather than being higher than backstop fossil technologies, is now close or competitive, though storage and grid challenges remain.
In 2017, the solar industry achieved SunShot's original 2020 cost target of $0.06 per kilowatt-hour for utility-scale photovoltaic solar power 3 years ahead of schedule, dropping from about $0.28 to $0.06 per kilowatt-hour (kWh) between 2010 and 2017.Similar gains may be realized in storage and smart grid technologies.Increasing regional 10.1029/2023AV001020 3 of 4 instability adds a national security dimension motivating decarbonization, and aviation is increasingly experimenting with biofuel and hydrogen energy sources.
The carbon-climate change equation is changing, from the 1990s Kyoto's challenge of "preventing dangerous interference" in the climate system to the far more concrete targets of the Paris Agreement.As the damages accrue and the cost of alternative technologies declines, the framing of mitigation as a risk to global economic growth is less certain, and the possibility that effective mitigation involving transition of the energy system could be inexpensive or a net benefit increases.Ethical and equity issues to mitigation choices most be addressed, but the economic tools available change as we see larger damages accruing rapidly and cheaper energy alternatives.
While climate change mitigation is often seen as being in opposition to free markets (Küppers, 2022), this emerging new equation suggests the contrary.
A New York Times article (NYT, 2022), explored how the high risk/lower cost scenario motivates changes to investments.The increasing impacts of climate on the world economy and on human welfare leads to an increasing and perhaps very high social cost of carbon, while unexpectedly rapid progress in decarbonization may be further accelerated by investment and the removal of barriers and perverse incentives, for example, by the recent US climate action.Two wrongs, an incorrect estimate of climate impacts (Yale, 2011) and overestimated costs of mitigation, could lead to a right, the effective mitigation of climate change at a affordable cost.
A world with an efficient transition to green energy may be not only more verdant but wealthier than the unmitigated world, as damages mount and mitigation costs drop.Science can play a role by identifying efficient pathways to decarbonization and assessing options conciastent with environmental justice.As the private sector realizes the wealth at risk to climate could be more than the cost of mitigation, a tipping point in human behavior could occur, unleashing the creativity and capital needed to decarbonize the energy system.

•
The global policy response to climate change has assumed that mitigation is expensive while adaptation is inexpensive • Recent data suggests both these assumptions are wrong, with costs mounting and the cost of green energy falling • Realizing that wealth at risk may exceed the cost of mitigation could drive a tipping point in human behavior global mean futures.Now, though, high risk from climate change is an everyday reality and even with vigorous mitigation, adaptation is needed.

Figure 1 .
Figure 1.Two faces of the problem: Changing costs of damage and mitigation.(a) Damages reported by the World Meteorological Organization for a range of climate-related events, showing costs of six types of climate-related damage (WMO, 2023).(b) The falling costs of solar energy.Data and empirical projections show projections have been consistently too conservative, leading to overestimated mitigation costs (Way et al., 2022).Note, photovoltaic module costs are re-scaled by 2.5 to match axes.