Climate Denial Crock of the Week

Katharine Hayhoe PhD on Linked In:

Human-caused climate change is affecting hurricanes in many ways, making them more dangerous and increasing the devastation they cause. We see these factors in play with Hurricane Fiona, that left much of Puerto Rico without power and wreaked havoc on coastal towns in Newfoundland; Typhoon Noru that intensified from a tropical storm to a Category 5 overnight and made a direct hit on a Philippine island; and now with the impacts of Hurricane Ian on Florida.

Hurricanes are naturally-occurring events, and we are not seeing more of them today than we used to. However, climate change is making them:

Intensify faster
Nature:
Both observed datasets show significant increases in tropical cyclone intensification rates in the Atlantic basin that are highly unusual compared to model-based estimates of internal climate variations. Our results suggest a detectable increase of Atlantic intensification rates with a positive contribution from anthropogenic forcing and reveal a need for more reliable data before detecting a robust trend at the global scale.

Stronger overall
Nature:
Here I define an index of the potential destructiveness of hurricanes based on the total dissipation of power, integrated over the lifetime of the cyclone, and show that this index has increased markedly since the mid-1970s. This trend is due to both longer storm lifetimes and greater storm intensities. I find that the record of net hurricane power dissipation is highly correlated with tropical sea surface temperature, reflecting well-documented climate signals, including multi-decadal oscillations in the North Atlantic and North Pacific, and global warming. My results suggest that future warming may lead to an upward trend in tropical cyclone destructive potential, and—taking into account an increasing coastal population—a substantial increase in hurricane-related losses in the twenty-first century.

Slow down
Nature:
Here I show that tropical-cyclone translation speed has decreased globally by 10 per cent over the period 1949–2016, which is very likely to have compounded, and possibly dominated, any increases in local rainfall totals that may have occurred as a result of increased tropical-cyclone rain rates. The magnitude of the slowdown varies substantially by region and by latitude, but is generally consistent with expected changes in atmospheric circulation forced by anthropogenic emissions. 

Shift Poleward
Nature:
When considered together, the trends in each hemisphere depict a global-average migration of tropical cyclone activity away from the tropics at a rate of about one degree of latitude per decade, which lies within the range of estimates of the observed expansion of the tropics over the same period.

Dump More Rain:
Geophysical Research Letters:
The effect of anthropogenic forcings can be detected in extreme precipitation observations, both individually and when simultaneously estimating anthropogenic and naturally forced changes. The effect of natural forcings is not detectable. We estimate that human influence has intensified annual maximum 1 day precipitation in sampled Northern Hemisphere locations by 3.3% [1.1% to 5.8%, >90% confidence interval] on average.

Also see here.

Damage Over Greater Area:
PNAS:
Our data reveal an emergent positive trend in damage, which we attribute to a detectable change in extreme storms due to global warming. 

Cost a lot more
World Weather Attribution:
In an additional step the scientists calculated what the monetary consequences of this increase in rainfall are and found that roughly $4 billion of the $10 billion damage in insured losses caused by the rainfall can be attributed to climate change.

In addition, extreme hurricane seasons in the Atlantic are becoming more frequent (https://lnkd.in/gCEzn4Pw) and the total amount of additional precipitation during a hurricane season attributable to climate change can be calculated (https://lnkd.in/g_jaTHDn).

And perhaps most importantly, for an individual hurricane such as Harvey, the science of attribution can now calculate how much more rain fell because of climate change (https://lnkd.in/gWK2iKKi), how much more area was flooded because of climate change (https://lnkd.in/g7qydbi6), how much larger the economic costs were because of climate change (https://lnkd.in/gVxKWyjz), and how unequally the impacts are distributed between higher- and lower-income communities (https://lnkd.in/gRCN_ceu).