Closing the gap: the impact of G20 climate commitments on limiting global temperature rise to 1.5°C

Under the Paris Agreement, Parties agreed to limit global temperature rise to well below 2°C, and pursue efforts to limit warming to 1.5°C. While some progress has been made in strengthening national climate targets and policies, current nationally national for reducing emissions are still insufficient to meet the Paris Agreement's temperature goal. Strengthened 2030 and mid-century commitments are urgently needed. The G20—a group collectively accounting for around 75 percent of global greenhouse gas (GHG) emissions, 80 percent of global GDP, and two-thirds of global population—has an outsized role to play in addressing climate change.This paper presents a set of scenarios that simulate different climate commitments made by G20 countries for 2030 and mid-century and the resulting impacts on global temperature rise. The analysis finds that if all G20 countries set ambitious, 1.5°C-aligned emission reduction targets for 2030 and reach net-zero emissions by 2050, global temperature rise at the end of the century could be limited to 1.7°C, keeping the 1.5°C goal within reach.

275 Candidates and 149 Validated Planets Orbiting Bright Stars in K2 Campaigns 0-10

Since 2014, NASA's K2 mission has observed large portions of the ecliptic plane in search of transiting planets and has detected hundreds of planet candidates. With observations planned until at least early 2018, K2 will continue to identify more planet candidates. We present here 275 planet candidates observed during Campaigns 0-10 of the K2 mission that are orbiting stars brighter than 13 mag (in Kepler band) and for which we have obtained high-resolution spectra (R = 44,000). These candidates are analyzed using the VESPA package (Morton 2012, 2015b) in order to calculate their false-positive probabilities (FPP). We find that 149 candidates are validated with an FPP lower than 0.1%, 39 of which were previously only candidates and 56 of which were previously undetected. The processes of data reduction, candidate identification, and statistical validation are described, and the demographics of the candidates and newly validated planets are explored. We show tentative evidence of a gap in the planet radius distribution of our candidate sample. Comparing our sample to the Kepler candidate sample investigated by Fulton et al. (2017), we conclude that more planets are required to quantitatively confirm the gap with K2 candidates or validated planets. This work, in addition to increasing the population of validated K2 planets by nearly 50% and providing new targets for follow-up observations, will also serve as a framework for validating candidates from upcoming K2 campaigns and the Transiting Exoplanet Survey Satellite, expected to launch in 2018.Comment: Published in AJ, 47 pages, 18 figures, 7 tables, associated supplementary dataset available at https://zenodo.org/record/116479

275 Candidates and 149 Validated Planets Orbiting Bright Stars in K2 Campaigns 0–10

Since 2014, NASA's K2 mission has observed large portions of the ecliptic plane in search of transiting planets and has detected hundreds of planet candidates. With observations planned until at least early 2018, K2 will continue to identify more planet candidates. We present here 275 planet candidates observed during Campaigns 0–10 of the K2 mission that are orbiting stars brighter than 13 mag (in Kepler band) and for which we have obtained high-resolution spectra (R = 44,000). These candidates are analyzed using the vespa package in order to calculate their false-positive probabilities (FPP). We find that 149 candidates are validated with an FPP lower than 0.1%, 39 of which were previously only candidates and 56 of which were previously undetected. The processes of data reduction, candidate identification, and statistical validation are described, and the demographics of the candidates and newly validated planets are explored. We show tentative evidence of a gap in the planet radius distribution of our candidate sample. Comparing our sample to the Kepler candidate sample investigated by Fulton et al., we conclude that more planets are required to quantitatively confirm the gap with K2 candidates or validated planets. This work, in addition to increasing the population of validated K2 planets by nearly 50% and providing new targets for follow-up observations, will also serve as a framework for validating candidates from upcoming K2 campaigns and the Transiting Exoplanet Survey Satellite, expected to launch in 2018

The First Post-Kepler Brightness Dips of KIC 8462852

We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the Kepler space mission in 2013 May. Our regular photometric surveillance started in October 2015, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1-2.5% dips, named "Elsie," "Celeste," "Skara Brae," and "Angkor", which persist on timescales from several days to weeks. Our main results so far are: (i) there are no apparent changes of the stellar spectrum or polarization during the dips; (ii) the multiband photometry of the dips shows differential reddening favoring non-grey extinction. Therefore, our data are inconsistent with dip models that invoke optically thick material, but rather they are in-line with predictions for an occulter consisting primarily of ordinary dust, where much of the material must be optically thin with a size scale <<1um, and may also be consistent with models invoking variations intrinsic to the stellar photosphere. Notably, our data do not place constraints on the color of the longer-term "secular" dimming, which may be caused by independent processes, or probe different regimes of a single process

Credibility gap in net-zero climate targets leaves world at high risk

Global climate policy is undergoing a rite of passage. What used to be a conversation about ambitious target setting now focuses increasingly on implementation and interventions to achieve these targets. This liminal transition from ambition to implementation is complex and presents deep ambiguities that are challenging for scientists to communicate and decision-makers to fathom. A critical question is whether we can believe that countries will deliver on the commitments they have made. By evaluating policy characteristics of countries’ net-zero targets, we can assign the targets credibility ratings, then estimate how greenhouse gas (GHG) emissions and temperature are differentiated by our confidence in the targets. When we consider the credibility of current climate pledges, our assessment shows that the world remains far from delivering a safe climate future

Credibility gap in net-zero climate targets leaves world at high risk

Looking at policies instead of promises shows that global climate targets may be missed by a large margin.</p

Emissions gap NDC and net zero findings after COP27

Analysis of the level and robustness of various government climate pledges, both 2030 NDCs and net zero goals. This repository contains the data required to run https://github.com/Rlamboll/Emissions_Gap. "Analysis_update_12_14 (2).xlsx" contains the 2023 assessment of net zero pledges by governments in terms of both their quality and content. "Data_forextensions_PostCOP27_master.xlsx" contains the estimates of emissions until 2030 based on NDCs after COP27, "Data_forextensions_EGR2023_master.xlsx" contains the updated version for the paper "Credibility gap in net-zero climate targets leaves world at high risk". "2022_emission_gap_temp_summary_data.csv" is the output of the complete process. Versions 1.0.0 and 1.0.1 are identical in terms of processing, but more data is uploaded for 1.0.1 with scenarios with additional carbon price increase rates. Version 1.1.0 contains the Data_forextensions_EGR2023_master file. Data and calculation are associated with the paper at DOI: 10.1126/science.adg624

State of Climate Action 2021: Systems Transformations Required to Limit Global Warming to 1.5°C

Limiting global warming to 1.5°C requires far-reaching transformations across power generation, buildings, industry, transport, land use, coastal zone management, and agriculture, as well as the immediate scale-up of technological carbon removal and climate finance. This report translates these transitions into 40 targets for 2030 and 2050, with measurable indicators.Transformations, particularly those driven by new technology adoption, often unfold slowly before accelerating after crossing a tipping point. Nearly a quarter of indicators assessed new technology adoption, with some already growing exponentially. This report considers such nonlinear change in its methodology.The transitions required to avoid the worst climate impacts are not happening fast enough. Of the 40 indicators assessed, none are on track to reach 2030 targets. Change is heading in the right direction at a promising but insufficient speed for 8 and in the right direction but well below the required pace for 17. Progress has stagnated for 3, while change for another 3 is heading in the wrong direction entirely. Data are insufficient to evaluate the remaining 9.This report also identifies underlying conditions that enable change—supportive policies, innovations, strong institutions, leadership, and shifts in social norms. Finance for climate action, for example, must increase nearly 13-fold to meet the estimated need in 2030