During the glacial–interglacial cycles of the past half million years, it took well over 50,000 years for continental ice sheets to grow to their maximum extent. In contrast, the transitions from glacial maximum to interglacial conditions generally occurred over about 10,000 years. In this web focus, we present a collection of overview, primary research and opinion pieces that explore the links between solar radiation, ice-sheet melting, ocean circulation and climate that govern the transition from glacial maximum to interglacial warmth.

Most volcanism on Earth occurs beneath the oceans, but submarine volcanoes are difficult to study. Advances in seafloor monitoring have opened up an unprecedented view of eruptions on the seabed. In this web focus we present opinion pieces and research articles that document the cycle of inflation and deflation, lava flows, and growth and collapse of two volcanoes beneath the Pacific Ocean during eruptions in 2011.

Where continents rift apart, new crust is formed from upwelling magma. Eventually, a new ocean basin forms. In this web focus we present opinion pieces, along with research and overview articles that explore the dynamic processes that occur during plate rifting. Case studies include both rifting on land, in east Africa and Iceland, and at the mid-ocean ridges that divide the oceanic crust.

Vegetation has been a key part of the Earth's surface for only about 450 million years. With the progression of the terrestrial landscape from bare surfaces to widespread coverage by plants - ground vegetation initially, then trees and finally flowering plants - the Earth's surface and its biogeochemical processes have also changed. In this issue, we present a collection of articles that explore how the evolution of terrestrial plants and the Earth's surface have affected each other.

Volcanic eruptions in the middle of tectonic plates, far from any volcanically-active plate boundaries, have created many of the thousands of ocean islands and seamounts that cover Earth's ocean floors. The geochemistry of their lavas may provide a window into processes occurring deep inside our planet. In this issue we collect research articles and opinion pieces that explore some possible mechanisms for the creation of ocean islands and seamounts, and highlight their connections to the deep and upper mantle.

Research into city living and its impacts is burgeoning, thanks to the fact that more than half of us now live in urban areas. In this web focus we compile a number of papers documenting some of the challenges associated with city life, and some of the less expected outcomes.

Future sea-level rise is uncertain, not least because it is unclear how, and how fast, the ice sheets in Greenland and Antarctica are going to respond to ocean and atmosphere warming. This collection of research papers, overview articles and opinion pieces highlights current understanding of the sensitivity of the planet's cryosphere to temperature rise, including a view back into the past and far into the future.

Understanding the amplitude of climate variability in the past, as well as the causes and mechanisms responsible for this variability is important in its own right. Yet it also helps us get a better idea of the range of possible Earth system responses to human-induced greenhouse gas emissions. In this web focus we explore the links between past climate and carbon cycle perturbations, along with the ability of state-of-the-art climate models to capture these links.

Deep-sea carbon cycling is poorly constrained, not least because this remote environment is so difficult to explore. In this web focus we highlight the prevalence and diversity of seabed carbon sources.

The January 2010 Haiti earthquake was catastrophic, leaving one million homeless. In this focus issue we have gathered articles — ranging from primary research to opinion pieces — that explore the physical processes responsible for the earthquake and the damage caused, as well as the humanitarian problems now facing the poorest country in the western hemisphere.

Soil is one of the most precious resources on the planet. As the global population grows, and the climate continues to warm, the structure and function of soils could change. In this focus issue we have gathered articles — ranging from primary research to opinion pieces — that explore the sensitivity of soils to climate and land use change, and that highlight the key role that soils play in shaping the environment and human society.

Arsenic-contaminated groundwater endangers the health of millions of people in southern Asia. In this focus issue we gather together articles on the origin and fate of arsenic in groundwater, together with opinion pieces outlining options for dealing with the problem, and backstories detailing some of the challenges faced by the researchers.