The land-grant model rests on three pillars that came together over the half-century between 1862 and 1914.

1. Accessible public higher education, provided by colleges of agriculture and engineering established in every state.
2. Fundamental and applied agriculture-related research, conducted and disseminated through a network of state agricultural experiment stations.
3. Cooperative extension, a Federal/state/county/university partnership that has placed agents in almost every county in the country with the mission of what the 1914 Smith-Lever Act calls the ‘diffusion and application’ of ‘useful and practical information’ related to ‘agriculture and home economics’.

These pillars parallel the tripartite mission of instruction, research, and service shared by almost all colleges and universities. A distinctive aspect of the land-grant model is the recognition, as noted in a 1930 report, that a core part of that service mission is to: bring people together for social intercourse, to study, to solve community problems, and to foster better relations towards a common endeavor.

Higher education institutions are particularly well-suited to this convening role because we are inherently networked, scale-spanning institutions.

• We have deep roots in our communities, while also being connected to global networks of peer institutions and researchers;
• We work to understand and solve problems today, while also training the people who will work to solve the world’s problems for the next half century.

And this model of bringing people together in our communities, linked to global knowledge networks, with one eye the present and one on the next generation – that is exactly what is needed to support communities, government, and the private sector in meeting the challenges of the climate crisis.

We’ve been moving in this direction at Rutgers, drawing upon both cooperative extension and the broader University. For example, over the last decade, we’ve convened an alliance of governments, communities, and businesses to understand and search for solutions to the state’s climate challenges. We’ve helped deploy nature-based solutions for coastal resilience. More recently, with state support, we set up the Climate Change Resource Center to leverage the expertise of the state’s entire higher ed sector to help tackle challenges like developing climate-smart municipal plans and more equitable state buyout strategies.

The genius of the land-grant model is that it recognizes that convening people to understand and solve problems is both a core university mission and a skilled activity that requires human capacity. It can’t be done adequately by moonlighting research and teaching faculty (like me) alone – you need a faculty of extension specialists and agents for whom convening people to link societal needs to university research and education is a primary job.

That is, frankly, a missing link in realizing higher ed’s potential as a catalyst of societal climate action.

Yes, quite a few universities now have a few climate translators who develop trusted relationships with partners and help bring people together to connect societal needs and university expertise.

But what’s missing is both scale and stability. The number of climate translators does not meet the demand, and relationships that take many years to build can easily disappear if project funding dries up, or even if a critical individual decides to retire.

Climate change is a decades and centuries long problem – relying centrally on a handful of people who are sometimes paid month to month is not a resilient solution for catalyzing climate action. This fragility creates costly inefficiency.

Contrast that with the land-grant model, which provides capacity funding for extension and use-inspired research, allowing faculty to develop decades-long relationships of trust. Because that funding is there, land-grant universities align their incentive structures to support research that directly helps solve real-world problems.

I believe that, with a land-grant-style and land-grant-scale investment in climate extension, we could really unlock the role of higher education as a catalyst of societal climate action.

We are facing at least three overlapping and intersecting crises, operating on different timescales: the four-hundred year crisis of racist violence in America, the immediate crisis of COVID-19 and the associated economic contraction, and the climate crisis, which has been building for over a century and has the potential to last for millennia.

All three require major societal efforts to mitigate, and all three are fiercely urgent: now is when justice impels us to address our country’s long-standing inequities, now is when we must figure out how to relaunch our economy safely after the COVID-induced pause, and now is when – if we wish to have any chance of meeting the climate goals laid out in the Paris Agreement – we must get the world on a path of declining greenhouse gas emissions.

To stabilize the climate, at any level of warming, we need net-zero global carbon dioxide emissions. To have a reasonable chance of limiting global warming to the Paris goal of 2°C, we need net global greenhouse gas emissions to drop by about 20% in this decade, and to fall to zero over the next five decades. And we need an even faster decline in the United States.

I do not think we are going to get multiple chances at this. I do not think there are going to be trillions of dollars of public funds invested to manage the COVID crises, and then trillions more invested in this decade to address the climate crisis. So, given the geophysical necessity of eliminating our carbon dioxide emissions in order to stabilize the climate, we have to make recovery investments count multiple times over, and address our multiple crises.

Nationally, the best blueprint out there, in my mind, comes from Data for Progress and from Evergreen Action, composed of many of the brilliant climate policy wonks who staffed Jay Inslee’s campaign Progress.

Their “Plan for a Clean Jumpstart to Rebuild America’s Economy” lays out 11 policies and $320 billion of investment to support state action, and another 21 areas for $1.2 trillion of direct federal investment. I want to highlight a few of the state-level initiatives that they call upon Congress to support as part of economic stimulus:

• expanding Low-Income Home Energy Assistance & Weatherization to support lower and middle-income households while advancing decarbonization
• letting states access DOE’s Clean Energy Loan Program financing and expanding DOE’s State Energy Program
• expanding block grants for state and local building upgrades and for hazard mitigation
• supporting transit systems

There are two items on the Evergreen menu that don’t require additional Federal action:

• tapping the Federal Reserve’s new Municipal Liquidity Facility to support investment programs like state Green Banks — noting that borrowing for capital expenditures, and especially capital expenditures that help us avoid the escalating economic damages from our current crises – is sounder fiscal policy than borrowing for operational expenditures

• leveraging the $15 billion provided by the CARES Act for “investments in all key disaster response and hazard mitigation needs under the Stafford Act” to advance the resilience priorities reflected in state Hazard Mitigation Plans – which could provide funds to put New Jerseyans safely back to work while also reducing exposure to growing hazards, such as the flooding and winds associated with hurricanes and Nor’easters. And these funds could be directed to priotize the risk to the most vulnerable.

I also think we have to think creatively about how to use the resources we have in New Jersey - especially because we can’t necessarily count on the federal government to rescue the states from the ongoing fiscal calamity. So we should be asking: how can we make the money we are spending do double or triple duty?

Prof. Keevey talked about the potential need for new taxes; I’m going to focus on the investment side, but I want to note that a $50/tonne carbon dioxide tax would raise over $4 billion for the state, while also incentivizing reductions in harmful greenhouse gas emissions –– money could be used to avoid some of the devastating cuts that might otherwise be on the table, and so perhaps offset the pro-cyclical effect of taxes.

One of the ideas for federal investment in the Clean Jumpstart plan is to create a National Climate Corps, modeled on the New Deal-era Civilian Conservation Corps, “to give young people the opportunity to serve in creating new public health and sustainability solutions in their own communities.”

I think this is a great idea. But I also think we already have a public system in this country that mobilizes over 15 million young people every year, including 200 thousand in New Jersey alone: the country’s system of public colleges and universities. And, partially as a result of COVID and partially as a result of longer-term financial trends, that system is facing its own crisis.

Why not put that system to work to solve real problems in real communities?

For those of you who are lawyers, think about how legal clinics work: students gain essential training by freeing wrongfully imprisoned persons, helping qualified immigrants receive asylum, ensuring children get educational services to which they are entitled, and so forth. Why not expand this model?

Indeed, we’ve been doing that at small-scale in the climate area for a few years at Rutgers. Our Coastal Climate Risk & Resilience graduate students take a studio course, in which they work with coastal communities to help them develop resilience plans. This past year, for example, our students worked with Perth Amboy to help them develop a resilience plan.

But C2R2, as we call it, is a small program – roughly a dozen students per year. How could we scale something like this up without increasing overall state expenditures?

Here’s a modest proposal:

Think of the total sum the state and local governments spend each year on intellectual services outsourced to the private sector. I’m not sure exactly how much the state spends on consultants, but it’s substantial.

Let’s take half of that and say we’re going to make that money not only buy us information we need, but also build up public and social sector capacity here in New Jersey. How do we do this?

Let’s give our state’s public research institutions option of first refusal on consulting studies. That’ll be easiest to manage if you have a clearinghouse that knows where relevant capacities are across the state’s research institutions and has the expertise to translate between researchers and end-users. And in the climate arena, such a clearinghouse was created by statute earlier this year: it’s one of our host organizations, the New Jersey Climate Change Resource Center.

Let’s use it so that, rather than renting expertise from private sector consultants based largely out of state, we’re using dollars spent on intellectual services to enhance public and social sector capacity here in New Jersey.

And let’s identify projects flowing through clearinghouses like the New Jersey Climate Change Resource Center could be teed up with enough advance notice that project-based clinical courses at institutions across the state could be arranged around them. And then that money would be doing triple duty:

1. Providing the knowledge decision-makers need to move forward
2. Building up public and social sector capacity to respond to decision-maker needs
3. Training the rising generation with the knowledge and the skills needed to solve the crises we are leaving to them

It’ll be great if we have national leadership that steps up to the crises we are facing at this moment and mobilizes the people and financial resources of the United States to address them. There’s a lot we can’t do as a state acting on our own. But there’s a lot we can do – especially if we make it a whole of society effort, with higher education institutions

The authors are asking a critically important question for small island states like the Marshall Islands, and they are leveraging important tools to study the effects of waves and sea-level rise on the island and its water resources. Unfortunately, some of the headline numbers from the paper – including how soon the 40 cm threshold will be crossed – are liable to misinterpretation because of the way the authors used some sea-level rise scenarios developed for the Department of Defense by the US government’s Coastal Assessment Regional Scenario Working Group (CARSWG)….

Nonetheless, the picture is grim, particularly under high-emissions scenarios…. Even under a 1.5°C stabilization scenario, it is likely that the groundwater supplies on Roi-Namur and other islands in the region will be rendered irrevocably contaminated within the lifetime of a 8-year-old child live in the Marshall Islands today. Thus a recent Frontline project dubbed the children of the Marshall Islands today “The Last Generation”.

Read more at Climate Impact Lab Insights.

Consider two roads. One leads to 2 feet of global-average sea-level rise over the course of this century, and swamps land currently home to about 100 million people. The other leads to 6 feet of rise, swamping the homes of more than 150 million. Our new study, published today in the journal Earth’s Future, finds that – at least from measurements of global sea level and continental-scale Antarctic ice-sheet changes – scientists won’t be able to tell which road the planet is on until the 2060s.

But our study also shows that the world can make the 2-foot road much more likely by meeting the Paris Agreement goal of bringing net greenhouse gas emissions to zero in the second half of this century. And through detailed studies of the local physics of ice-sheet changes and more refined reconstructions of ice-sheet changes during warm periods of the geological past, scientists may become able to distinguish between the two roads sooner.

Until then, though, decision-makers at all scales – from homeowners to governments — should plan for the future cognizant of this ambiguity.

The new findings stem from an analysis that links a widely-used framework for projecting how sea level around the world will respond to climate change to a model that accounts for recently identified processes contributing to Antarctic ice loss.

Read more at Climate Impact Lab Insights.

[C]limate fiction can play a critical role in the face of the large-scale experiment we humans are conducting with the world’s climate system: inspiring creative rethinks of the designs and technologies needed to reshape how we relate to our environment.

Science tells us that, by reshaping our global energy and agricultural systems, we can avoid the magnitude of planetary change that Robinson depicts. But to make those changes and to adapt to the changes we don’t avoid, the world’s best minds need to focus, not on new apps or financial innovations, but on the civilizational challenges at hand.

Works like Robinson’s – starkly beautiful and fundamentally optimistic visions of technological and social change in the face of some of the worst devastation we might bring upon ourselves – can inspire that focus in a way that myopic discussions of the near term or grim, apocalyptic tales cannot.

I will also be on a panel at Rutgers-New Brunswick with Kim Stanley Robinson and with other Rutgers faculty discussing this novel on April 5.

I presented an talk on past, present, and future sea-level rise and climate risk to the Rutgers Institute of Earth, Ocean and Atmospheric Sciences in October. The video is now available on Rutgers’ Youtube channel.

• R. E. Kopp, A. C. Kemp, K. Bittermann, B. P. Horton, J. P. Donnelly, W. R. Gehrels, C. C. Hay, J. X. Mitrovica, E. D. Morrow, and S. Rahmstorf (2016). Temperature-driven global sea-level variability in the Common Era. Proceedings of the National Academy of Sciences. doi: 10.1073/pnas.1517056113.

In this paper, we use a new statistical framework (based on spatio-temporal empirical hierarchical modeling with Gaussian processes; code available at Github) to identify the common global signal in a new database of >1300 geological sea-level indicators from 24 localities around the world. To our knowledge, this paper represents the first attempt to combine statistically rigorous analysis methods and a global proxy database to reconstruct global sea-level change over this time period.

What does the study find?

The paper has four key findings.

First, the rate of global sea-level change in the 20th century (1.4 ± 0.2 mm/yr) was, with 95% probability, faster than during any century since at least 800 BCE. (And the 800 BCE date is not because the rate of global sea-level rise was probably faster before then, but simply that the reconstruction quality isn’t good enough before then to have the same level of confidence.)

Second, the 20th century wasn’t the only time period when temperature and global sea level changed together. Global sea level underwent a statistically robust fall of 8 ± 8 cm (95% probability interval) over 1000-1400 CE, coincident with a decline in global temperature of ~0.2°C. Notably, both the decline in sea level and the decline in temperature occurred during the so-called European “Medieval Warm Period,” providing additional evidence that the “Medieval Warm Period” and “Little Ice Age” were not globally synchronous phenomena.

Third, using a ‘semi-empirical’ statistical model calibrated to the relationship between temperature and global sea-level change over the last 2000 years, we find that, in alternative histories in which the 20th century did not exceed the average temperature over 500-1800 CE, global sea-level rise in the 20th century would (with >95% probability) have been less than 51% of its observed value. We suggest that this counterfactual is consistent with what the world might have been like in the absence of anthropogenic warming. (A separate study led by my collaborator Ben Strauss at Climate Central uses our results to examine the contribution of the anthropogenic sea-level contribution to nuisance flooding in the United States.)

Fourth, the new semi-empirical model reconciles the remaining discrepancies between the physical process models preferred by the IPCC’s Fourth and Fifth Assessment Reports and semi-empirical models. The semi-empirical results are consistent with the localized projections that our team presented in a 2014 Earth’s Future paper. This agreement should lend greater confidence to these projections (about 50–130 cm of very likely 20th century global sea-level rise under the high-emissions RCP 8.5 pathway).

However, there is a caveat: semi-empirical models are inherently calibrated to the historical experience, and potentially biased if the processes that will dominate sea-level change in the future are qualitatively different from those that drove it in the past. In the Common Era before the 21st century, changes in ocean heat content and in mountain glaciers were likely the main drivers of global sea-level change. Ice sheets – and, in particular, ocean interactions with ice sheet margins – are playing an increasingly important role and dominate uncertainty in global sea-level rise projections in the second half of this century. Thus, the agreement between the new semi-empirical model and the physical models could be taken as suggesting that both share a common historical bias. For example, some exciting work being done by David Pollard and Rob DeConto suggests that processes such as ice-cliff collapse and ice-shelf hydrofracturing may play important roles in future ice sheet behavior that have not been well incorporated into most ice sheet models.

For the moment, though, the projections of global and local changes made by the new paper and by our 2014 paper remain among the best available probabilistic projections. Nonetheless, the ice-sheet response to global warming remains an area of what risk analysts call ‘deep uncertainty’. There is an indeterminate but non-zero probability that our estimated probability distributions are excessively conservative, particularly toward the end of the century and beyond. Thus, I would suggest that decision makers use these ‘best-available’ distributions but also consider the consequences for their decisions of ‘worst-case’ sea-level rise scenarios (e.g., about 2.5 m globally in the course of the century according to Kopp et al., 2014). If the consequences of such a worst-case scenario are unacceptable, then decision makers should adopt strategies that are robust to this possibility. Such robust strategies generally shouldn’t involve treating the worst case as a certainty; rather, in many cases, they will involve ‘adaptive’ strategies that allow for tightening of protection should sea-level rise prove to be toward the high end of projections.

What’s new relative to previous work?

The IPCC’s assessment of the literature, prior to our study, was that global sea-level fluctuations over the last 5 millennia were <± 25 cm, and that there was no clear evidence of whether specific fluctuations seen in some regional sea level records reflected global changes. The new paper places tighter constraints on variability over the last 3 millennia and identifies global fluctuations.

Previous attempts to reconstruct global sea level over the last 2-3 thousand years have relied on one of three approaches.

Some studies have used records of local sea-level change, attempted to correct them for processes (such as the ongoing response to the end of the last ice age) that are approximately steady over this time period, and added some additional uncertainty to account for the fact that local sea-level variability can differ for a variety of reason from global sea-level change. A good example of this approach is the study of Kemp et al. (2011), based on records from North Carolina, which involved a number of authors of the new study.

Some studies have attempted to manually tune the parameters of physical models that relate ice sheet changes to sea-level changes; the best recent example of this was the study of Lambeck et al. (2014), which covered the last 20,000 years. Such studies have not generally employed modern statistical methodologies, and generally have not focused on the last 2-3 millennia. Lambeck’s study, for instance, included only 31 geological data points from the last millennium (1000-2000 CE), compared to 790 such data points in our study.

Some studies have attempted to estimate the statistical relationship between temperature and global sea level seen in the period for which tide gauge records exist (the last 2-3 centuries) and then, using geological reconstructions of past temperature changes, extrapolate backward (‘hindcast’) past sea-level changes. The study of Grinsted et al. (2010), which significantly overestimated the responsiveness of sea-level to temperature change, is a good example.

Related coverage

• My co-author Stefan Rahmstorf’s blog post at RealClimate
• Rutgers Today article
• News articles: Associated Press, Bloomberg, Climate Central, Gizmodo, Mashable, New York Times, Washington Post

UPDATE (March 3): Our paper has gotten stellar coverage, including leading the New York Times on February 23 and meriting a mention by @BarackObama on March 1:

We're seeing the fastest rise in sea-levels in nearly 3,000 years: https://t.co/MwO2QKE4GW #ActOnClimate

— Barack Obama (@BarackObama) March 1, 2016

The death toll is still being tallied, and many heat-related deaths will be recognized only after the fact. Yet it’s already the deadliest heat wave to hit India since at least 1998 and, by some accounts, the fourth- or fifth-deadliest worldwide since 1900.

As of June 2, Reuters was reporting about 2,500 deaths during the heat wave. The EM-DAT database tabulates

1. Europe, July-August 2003: 72,210 direct deaths
2. Russia, June-August 2010: 55,736 direct deaths
3. Europe, June-July 2006: 3,418 direct deaths
4. India, May 1998: 2,541 direct deaths

(These numbers are based on our parsing of the database – the numbers are slightly different than those listed in Jeff Masters’ nice post on the Indian heat wave.)

These numbers differ somewhat from those we quote in the text for Europe 2003 and Russia 2010, as we drew upon two studies that (1) estimated excess mortality, not just deaths directly identified as being tied to the heat wave, and (2) drew somewhat narrower time windows to focus around the main body of the heat waves.

The July 1995 heat wave in the Midwest caused over 700 deaths in Chicago. The August 2003 heat wave in western Europe led to about 45,000 deaths. The July-August 2010 heat wave in western Russia killed about 54,000 people.

The Chicago number comes from Whitman et al. (1997). The western Europe number comes from Robine et al. (2008); the August total in that paper is 44,878, although a total of 71,449 excess deaths are estimated for the summer as a whole. The Russia numbers are from Revich (2011).

In the Indian state of Andhra Pradesh, the highest wet-bulb temperatures of the latest heat wave have peaked around 86 degrees — levels approaching the worst of the 1995 Midwest heat wave, which set records in the United States for humid heat.

These numbers are based on Jon’s own calculations, using meteorological observations from Weather Underground and his HumanIndexMod code. HumanIndexMod calculates wet-bulb temperature using an algorithm with inputs of atmospheric moisture, surface pressure, and air temperature.

The plots below show the daily maximum and minimum wet-bulb temperatures for Kakinada, Andhra Pradesh, this past month. It’s worth noting that there are days when wet-bulb temperature didn’t fall below 82°F – a truly miserable situation, affording no opportunity to cool off.

In work one of us (Robert Kopp) led for the Risky Business Project, we found that over the period from 1981 to 2010, the average American experienced about four dangerously humid days, with wet-bulb temperatures exceeding 80 degrees. By 2030, that level is expected to more than double, to about 10 days per summer. Manhattanites are expected to experience nearly seven uncomfortably muggy weeks in a typical summer, with wet-bulb temperatures exceeding 74 degrees, about as many as residents of Washington have experienced recently.

These results come from the forthcoming book Economic Risks of Climate Change: An American Prospectus, much of the text of which is available as a report at ClimateProspectus.org. The wet-bulb temperature projections are detailed in the section on ‘Humidity’ in chapter 4; the numerical projections are detailed further in the data tables available at the same site. Results for the ‘average American’ refer to a population-weighted average of county-level values across the U.S. Results for New York City are taken as the average of the values provided in the data tables for Connecticut and New Jersey, as the New York state values are biased by conditions upstate. The ‘uncomfortable’ and ‘dangerous’ conditions refer to Categories I and II on the American Climate Prospectus (ACP) Humid Heat Stroke Index; the conditions in Kakinada were skirting close to Category III (‘extremely dangerous’).

The American Climate Prospectus analysis is probabilistic: it comes up with probability distributions over space and time for the different physical and economic variables analyzed. The results presented in the column are ‘expected’ in the statistical sense; that is to say, they represent the probability-weighted average across possible future states of the world.

Since we can’t avoid it now, we must make our communities more resilient to heat and humidity extremes. One step is to expand access to air-conditioning for those who can’t afford it. We must also improve cooling in stiflingly hot factories and warehouses, strengthen public health systems, improve public warnings when heat and humidity are dangerously high, and be willing to shift outdoor work schedules.

There are some additional options we didn’t have space to mention here. These include technologies for passively cooling buildings and urban areas, such as cool roofs and pavements, as well as the broader set of energy efficiency measures to reduce the need for active cooling.

If we choose not to reduce emissions of heat-trapping gases and instead continue to rely upon fossil fuels, the average American could expect to see about 17 dangerously humid days in a typical summer in 2050 and about 35 in 2090.

The results here are for continued fossil-fuel-intensive growth, represented by Representative Concentration Pathway (RCP) 8.5. (See discussion of RCPs below.)

Some summers would have days so stiflingly muggy that a healthy individual would suffer heat stroke in less than an hour of moderate, shaded activity outside.

These stiflingly muggy days are Category IV (‘extraordinarily dangerous’) on the ACP Humid Heat Stroke Index, with wet-bulb temperatures exceeding 92°F. Such days have no precedent in U.S. history. In the ACP analysis, they are expected with 6%/year probability in Illinois and 1%/year probability in New Jersey under RCP 8.5 in 2040-2059. By 2080-2099, 4 such days are expected per summer in Illinois and 1 such day in New Jersey. The average American is expected to experience such a day with 1%/year probability in 2040-2059 and 80%/year probability in 2080-2099.

About an hour of shaded, 150-watt activity at a wet-bulb temperature of 92°F leads to skin temperatures of 100°F and core body temperatures of 104°F (the threshold for heat stroke), based on a Danish study conducted on twelve trained, male endurance athletes, ages 23–34. 150 watts corresponds to ‘moderate effort’ on a stationary bike – about 40% of maximal aerobic capacity for these individuals. The athletes, dressed only in swim trunks and shoes, were asked to pedal to exhaustion on a stationary bike in a room with an air temperature of 95°F and relative humidity of 87%, corresponding to a wet-bulb temperature of about 91°F. After 45 ± 3 minutes of exercise without acclimation, or 52 ± 2 minutes with acclimation, these individuals reached exhaustion and a core temperature of 103.8 ± 0.2°F.

And carrying on this way through the 22nd century locks in a trajectory where summer outdoor conditions could become physiologically intolerable for humans and livestock in the eastern United States — and in regions currently home to more than half the planet’s population.

This remark is based upon a 2010 paper Matt co-authored with Steven Sherwood. This study found that conditions physiologically intolerable for humans (conservatively defined there as areas with peak wet-bulb temperatures exceeding 95°F during the peak of the summer, well into ACP Category IV, and well beyond the current planetary experience) cover regions home to more than half the planet’s population with about 11°C (20°F) of global warming. The regions affected include much of the eastern U.S., China, India, Brazil, and north Africa. Based on simulations with the MAGICC simple climate model, as run for the ACP, such conditions have about a 20% chance of being realized by 2200 under RCP 8.5.

But this fate is not yet locked in. Moderate reductions in emissions of heat-trapping gases — sufficient to stop global emissions growth by 2040 and bring emissions down to half their current levels by the 2070s — can avoid those paralyzing extremes and limit the expected late-century experience of the average American to about 18 dangerously humid days a year. And strong reductions — bringing global emissions to zero by the 2080s — can cap the growth of humidity extremes by the midcentury.

The two alternative pathways referred to here are RCP 4.5 and RCP 2.6, shown alongside RCP 8.5 and historical emissions below. The RCPs are the current standard pathways of emissions used by the climate modeling community. For reasons a little too complicated to get into here, they don’t directly correspond to socio-economic scenarios, but RCP 4.5 is somewhat below what is possible to achieve in the absence of climate policy and RCP 2.6 requires quite severe reductions in greenhouse gas emissions, with global emissions begin to decline in the 2020s. RCP 2.6 is the pathway most consistent with the 2°C temperature target to which the nations of the world have notionally agreed in the 2009 Copenhagen Accord and the 2010 Cancun Agreements.