Summary for policymakers Technical summary 1. The climate system - an overview 2. Observed climate variability and change 3. The carbon cycle and atmospheric CO2 4. Atmospheric chemistry and greenhouse gases 5. Aerosols, their direct and indirect effects 6. Radiative forcing of climate change 7. Physical climate processes and feedbacks 8. Model evaluation 9. Projections of future climate change 10. Regional climate simulation - evaluation and projections 11. Changes in sea level 12. Detection of climate change and attribution of causes 13. Climate scenario development 14. Advancing our understanding Glossary Index Appendix.

Climate change 2001: the scientific basis

The planetary boundaries framework defines a safe operating space for humanity based on the intrinsic biophysical processes that regulate the stability of the Earth system. Here, we revise and update the planetary boundary framework, with a focus on the underpinning biophysical science, based on targeted input from expert research communities and on more general scientific advances over the past 5 years. Several of the boundaries now have a two-tier approach, reflecting the importance of cross-scale interactions and the regional-level heterogeneity of the processes that underpin the boundaries. Two core boundaries—climate change and biosphere integrity—have been identified, each of which has the potential on its own to drive the Earth system into a new state should they be substantially and persistently transgressed.

/pdf/planetary-boundaries-guiding-human-development-on-a-changing-5gmf909etg.pdf

Planetary boundaries: Guiding human development on a changing planet

Increasing population and consumption are placing unprecedented demands on agriculture and natural resources. Today, approximately a billion people are chronically malnourished while our agricultural systems are concurrently degrading land, water, biodiversity and climate on a global scale. To meet the world's future food security and sustainability needs, food production must grow substantially while, at the same time, agriculture's environmental footprint must shrink dramatically. Here we analyse solutions to this dilemma, showing that tremendous progress could be made by halting agricultural expansion, closing 'yield gaps' on underperforming lands, increasing cropping efficiency, shifting diets and reducing waste. Together, these strategies could double food production while greatly reducing the environmental impacts of agriculture.

https://escholarship.org/content/qt6xw5g085/qt6xw5g085.pdf?t=ovfwpc

Solutions for a cultivated planet

Background:
VSEARCH is an open source and free of charge multithreaded 64-bit tool for processing and preparing metagenomics, genomics and population genomics nucleotide sequence data. It is designed as an alternative to the widely used USEARCH tool (Edgar, 2010) for which the source code is not publicly available, algorithm details are only rudimentarily described, and only a memory-confined 32-bit version is freely available for academic use.

Methods:
When searching nucleotide sequences, VSEARCH uses a fast heuristic based on words shared by the query and target sequences in order to quickly identify similar sequences, a similar strategy is probably used in USEARCH. VSEARCH then performs optimal global sequence alignment of the query against potential target sequences, using full dynamic programming instead of the seed-and-extend heuristic used by USEARCH. Pairwise alignments are computed in parallel using vectorisation and multiple threads.

Results:
VSEARCH includes most commands for analysing nucleotide sequences available in USEARCH version 7 and several of those available in USEARCH version 8, including searching (exact or based on global alignment), clustering by similarity (using length pre-sorting, abundance pre-sorting or a user-defined order), chimera detection (reference-based or de novo), dereplication (full length or prefix), pairwise alignment, reverse complementation, sorting, and subsampling. VSEARCH also includes commands for FASTQ file processing, i.e., format detection, filtering, read quality statistics, and merging of paired reads. Furthermore, VSEARCH extends functionality with several new commands and improvements, including shuffling, rereplication, masking of low-complexity sequences with the well-known DUST algorithm, a choice among different similarity definitions, and FASTQ file format conversion. VSEARCH is here shown to be more accurate than USEARCH when performing searching, clustering, chimera detection and subsampling, while on a par with USEARCH for paired-ends read merging. VSEARCH is slower than USEARCH when performing clustering and chimera detection, but significantly faster when performing paired-end reads merging and dereplication. VSEARCH is available at https://github.com/torognes/vsearch under either the BSD 2-clause license or the GNU General Public License version 3.0.

Discussion:
VSEARCH has been shown to be a fast, accurate and full-fledged alternative to USEARCH. A free and open-source versatile tool for sequence analysis is now available to the metagenomics community.

/pdf/vsearch-a-versatile-open-source-tool-for-metagenomics-3dmyvav0wl.pdf

VSEARCH: a versatile open source tool for metagenomics

Changes in Atmospheric Constituents and in Radiative Forcing

J. C. Schroder1, S. J. Hanna1, R. L. Modini2, A. L. Corrigan2, S. M. Kreidenweis6, A. M. Macdonald3, K. J. Noone5, L. M. Russell2, W. R. Leaitch4, and A. K. Bertram1 1Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada 2Scripps Institute of Oceanography, University of California-San Diego, La Jolla, San Diego, CA, USA 3Air Quality Processes Research Section, Environment Canada, Toronto, ON, Canada 4Climate Chemistry and Measurements Research, Environment Canada, Toronto, ON, Canada 5Department of Applied Environmental Science, Stockholm University, Stockholm, Sweden 6Department of Atmospheric Science, Colorado State University, Fort Collins, CO, USA

/pdf/corrigendum-to-size-resolved-observations-of-refractory-35nmdmn1ei.pdf

Corrigendum to "Size-resolved observations of refractory black carbon particles in cloud droplets at a marine boundary layer site" published in Atmos. Chem. Phys., 15, 1367–1383, 2015

This chapter examines different methods for dealing with “unknown unknowns,” the differences between risk, uncertainty, and surprise. We examine different approaches for handling events that have a low (potentially even unknown) probability of occurring, but the consequences of which would be very large. We look at some of the potential tipping points in the marine system and show how a risk framework would be a better way of approaching these risks than simply trying to assess the uncertainty of the behavior in marine systems. We contrast three different approaches to developing scenarios for the future (approaches used by the IPCC, Shell, and the U.S. military) and examine what lessons can be learned in terms of how to peer into a murky future for global marine systems.

Tipping Points, Uncertainty, and Precaution: Preparing for Surprise

Cloud droplet redisual particles in cirrus clouds

The ECN contribution to the Ground-based Cloud Experiments (GCE) comprised measurements of the droplet spectra and of gases like NH3 and HNO3. In a wind tunnel/cloud chamber several fog samplers and optical instruments have been calibrated and characterised.

Kevin J. Noone

Papers

Corrigendum to "Size-resolved observations of refractory black carbon particles in cloud droplets at a marine boundary layer site" published in Atmos. Chem. Phys., 15, 1367–1383, 2015

Tipping Points, Uncertainty, and Precaution: Preparing for Surprise

Cloud droplet redisual particles in cirrus clouds

Individual Results from GCE Principal Investigators