First, the energy sector. We're mostly talking methane leaks during the production, storage and transport of coal, oil, and (especially) natural gas. Fixing the leakage problem is more than affordable - it's actually profitable, because leaks cost Big Energy potential revenue to be gained from converting methane to more benign products. The reason why companies haven't moved more quickly to take advantage of this business opportunity is the upfront expense of equipment upgrades that would shut down the leaks. Making money costs money.
Home to methane-spewing microbes, wetlands are the largest source of methane emissions in the world.
Diesel transportation and household burning of solid fuels together account for almost 60% of global black carbon emissions. Transitioning to cleaner, more efficient transportation and household technologies would go a long way to making a serious dent in BC emissions.
This post will the first of many addressing the second lever: reduce emissions of short-lived climate pollutants (SLCPs). The main SLCPs are black carbon, methane, tropospheric ozone, and some hydrofluorocarbons.
But will the gains erode without additional mandates? I don't know. Sometimes you need to push to get the ball rolling, but do you need to continue pushing with the same force for the ball to accelerate? We're about to find out (or at least get some relevant data) from the US example, where the mandates are being emasculated.
Unfortunately, a rise of 3.5°C could very well be catastrophic for our planet long before we even hit the 3.5 degree mark or get to 2100. Better to keep warming within 1.5°C...
So what did this 'carbon budget' paper actually say? That various climate models have projected slightly more warming for slightly less cumulative CO2 than what the authors have seen in the real world, so there’s a teeny bit more wiggle room for achieving the goal of no more than 1.5° C warming this century, assuming very aggressive Green House Gas (GHG) mitigation efforts.
Consuming experiences instead of things sounds so virtuous and life-enriching. Forget bling, raft down the Amazon! Have a culinary adventure in Thailand! Problem is, consumable experiences are often the kind that are bad for the planet, e.g. travel and dining out. What to do?
I’m tempted to say “Estimating economic damage from climate change in the United States” is a noble failure, a well-meaning endeavor of questionable value due to a few missteps. But I don’t believe it. What I believe is that the authors deliberately chose implausible worst-case assumptions because the resulting projections of economic damage would be more likely to spur policy action than more plausible middle-of-the-road assumptions.
...we may have already reached "peak farm" as “the ratio of arable land per unit of crop production shows improved efficiency of land use, the number of hectares of cropland [having] scarcely changed since 1990” (Ausubel, Wernick, & Waggoner, 2013). This despite an additional two billion mouths to feed in the last 25 years.
RCP8.5 also comes with a storyline that would be consistent with such high GHG concentration levels by the end of this century. The storyline is a set of socio-economic assumptions that provide a narrative for how we might get from here to there. The storylines aren’t carved in stone; different socio-economic developments could lead to the same climate change outcome – but to be taken seriously, a storyline has to be plausible.
[The authors] predict that by 2100 the poorest third of US counties, mostly in the south, will experiences significant damage due to climate-related effects on agriculture, crime, coastal storms, energy, human mortality, and labor. They project this damage will occur “under business-as-usual emissions (Representative Concentration Pathway 8.5)”. In other words, the authors’ analysis is based on a particular global emissions scenario unfolding. If we are to put stock in their projections, we need to consider the plausibility of their assumptions. The output is only as good as its input.
...the authors don't explain what "Representative Concentration Pathway 8.5" is, except to say it's a "business-as-usual" emissions scenario. You can't really evaluate the paper without some idea of what RCP8.5 is and whether it's a likely scenario for global emissions trends.
The International Energy Agency has a nice list of policy recommendations to speed up adoption of energy-efficient technology and practices. They estimate that if implemented globally without delay, their proposed actions could save as much as 7.6 gigatonnes (Gt) CO2/year by 2030 – "almost 1.5 times current US annual CO2 emissions."
I am not a climate change skeptic although I have the utmost respect for those that keep the torch of skepticism alive (minus the cranks). Saying I'm not a skeptic doesn't mean I've read all the science, understand the physics, and evaluated the climate projections based on my extensive knowledge of climate models. It means I'm using a heuristic: when 90% (give or take) of a group of experts say something is so, it probably is so. Nothing to pat myself on the back about. Not going to crow: I am more science-y than thou.
What is the right question? Something along the lines of what the Pew survey asked: assuming climate change is happening, are humans the primary cause of global warming? The Verheggen et al paper comes closest to having both the right question and the appropriate respondents. Plus, they had the largest sample size - more than the other three studies combined. And they found a roughly 90% endorsement of anthropogenic global warming.
It also makes a world of difference when the scientific consensus on climate change is represented as nearly unanimous (e.g., 97%) rather than merely a large majority (e.g., 90%). The former intimidates and discourages potential dissent; the latter, not so much.
The Bray and von Storch 5th International Survey of Climate Scientists consists of over a hundred statements related to climate change and its effects. For each statement, respondents indicated their level of agreement or opinion via a seven-point scale. Around a third of the 651 respondents were involved (as author, reviewer, etc.) with the United Nations Intergovernmental Panel on Climate Change Fifth Assessment Report (2014 IPCC AR5).
Of the scientists convinced or confident that climate change is occurring, 48% were convinced that most of the recent or near future climate change is the result of anthropogenic causes; 26% were very confident of this; and 14% were modestly confident.
...only those authors who self-rated their papers as having an opinion on anthropogenic global warming (AGW) were asked if they personally endorsed AGW themselves. These authors represented 62.7% of the whole sample - 746 out of 1189 respondents. The authors who self-rated their papers as having no position on AGW were not asked about their opinion on global warming. They were also climate scientists...