MORE STABLE, MORE SAFE – K2 NORTH SIDE’S CLIMATE

OUR OPINION IS THAT IT OFFERS A SAFER WAY UP K2 THAN THE SOUTHERN SIDE, THOUGH MORE TECHNICAL, REMOTE AND EXPENSIVE!

GREG CHILD, 1990

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ALTHOUGH RUMORS PERSIST ABOUT K2’S CHINESE NORTH SIDE BEING DANGEROUS*, THOSE IN THE KNOW HAVE FOR DECADES KNOWN IT’S SAFER. THOUGH THE APPROACH HAS SOME EXTRA FACTORS THAT CAN INVOLVE RISKS, A BASIC LOOK AT THE ENVIRONMENTAL FACTORS ON THE NORTH SIDE – BACKED UP BY THE TEAMS THAT HAVE BEEN THERE – IMMEDIATELY SHOW WHY IT’S SAFER.

BEYOND THE INHERENT FACT THAT THE NORTH RIDGE IS A SINGLE ARETE THAT PASSES ABOVE THE HIGH SERACS, THE GRADIENT OF THE NORTH RIDGE MEANS LITTLE SNOW ACCUMULATES ON IT, RESULTING IN FREQUENT SMALLER ‘SHEDDING EVENTS’ RATHER THAN THE LARGER CHANNELLED AVALANCHES DOWN ENORMOUS CHUTES THAT DEFINE THE SOUTH SIDE ROUTES. THIS SHEDDING IS NOT JUST THE RESULT OF THINGS BEING STEEPER, IT IS ALSO THE RESULT OF THE NORTH SIDE’S ENVIRONMENT BEING LESS CONDUCIVE TO THE CONSOLIDATION OF DEEP SNOW BY HAVING LESS EXPOSURE TO SOLAR RADIATION, COOLER AMBIENT TEMPERATURES, 25% LESS PRECIPITATION OVER THE NON-CLIMBING SEASON, & A SEASON WITH FEWER DAYS ABOVE FREEZING. ADD IT ALL UP AND YOU SEE WHY GREG CHILD’S TEAM THAT INCLUDED STEVE SWENSON & GREG MORTIMER SAID WHAT THEY DID (AND THE ONE FACTOR WE CAN CHANGE – THE EXPENSE – WE HAVE).

MOST OF THESE FACTORS ARE COMMON TO ALL NORTH FACE ROUTES (IN THE NORTHERN HEMISPHERE) AND WILL BE FAMILIAR TO CLIMBERS WHO HAVE LEARNED THEIR SKILLS IN THE ALPS, ALASKA ETC, BUT TO THE CLIMBER RAISED ON THE TRADE ROUTES OF COMMERCIAL 8000m TRIPS MAY NEVER HAVE BEEN MADE APPARENT.

ALL GRAPHICS FROM METEOBLUE. DATA ALTITUDES ARE AROUND BASECAMP / CAMP I LEVELS.

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SOLAR RADIATION

CLIMBERS CAN MISTAKE MORE SUNNY DAYS FOR BETTER CONDITIONS, AND AT LOWER ALTITUDES THIS CAN BE TRUE. BUT ABOVE ABOUT 4000m WHERE TEMPERATURES SEE LESS TIME ABOVE FREEZING, UV & THERMAL RADIATION BECOMES THE PRIMARY WAY ICE BREAKS DOWN (NOTING THERMAL RADIATION REACHING A SURFACE INCREASES SIGNIFICANTLY WITH LESS ATMOSPHERE TO ABSORB IT). THE STEEPNESS OF THE NORTH RIDGE EQUATES TO MORE EXPOSED ROCK, SOMETHING ALSO AFFECTED BY THERMAL RADIATION AND THE WAY IT LEADS TO DELAMINATION BY FORMING A TEMPERATURE DIFFERENTIAL WITH THE ICE.

NUMBER OF SUNNY DAYS IS A USEFUL METRIC BUT THE FUNDMENTAL ASPECT OF THE ROUTE MATTERS AS MUCH TOO. THE NORTH RIDGE IS SHADED UNTIL LATER, IN PART BEING PROTECTED BY THE EAST RIDGE, AND EVEN WHEN RECEIVING FULL SUN THE SUN IS AT A MUCH LOWER ANGLE FURTHER HEIGHTENED BY THE ROUTES STEEP GRADIENT. COMBINED THESE FACTORS.

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TEMPERATURES

WARMER CERTAINLY DOESN’T EQUATE TO BETTER AND ANYONE WHO HAS BAKED IN THE HEAT OF K2’S SOUTHERN ROUTES CAN ATTEST TO THAT. AMBIENT TEMPERATURE PLAYS A BIG ROLE IN THE WAY THINGS ARE DONE, ESPECIALLY IN THE LOWER 2/3 OF AN 8000m PEAK WHEN TEMPERATURES ABOVE FREEZING ARE WHAT CAUSES THINGS TO MOVE. DISTINCT FROM SOLAR RADIATION, AMBIENT TEMPERATURE REFERS TO THE LARGER AIR MASS THAT SITS OVER A FACE THAT’S SEASONAL AND INFLUENCED BY FACTORS OFTEN FAR FROM THE MOUNTAIN (FOR EXAMPLE DOWN THE INDUS OR SHAKSGAM VALLEYS). HIGHER AMBIENT TEMPERATURES CREATE EXPANDING MASSES OF MOISTURE THAT CONDENSE INTO THE AFTERNOON CLOUD, AND THE NORTH THAT HAS LOWER TEMPERATURES SEES THIS LESS DRAMATICALLY. BEING AVERAGE 5c COOLER THAN THE SOUTH MEANS THE NORTH RIDGE EFFECTIVELY SKIPS THE MOST VOLATILE WEATHER PERIOD SEEN ON THE SOUTH. 5c REPRESENTS 50% OF THE NORTH SIDES TEMPERATURE RANGE ABOVE FREEZING, WHICH TRANSLATES INTO SEVERAL HOURS A DAY IN THE SAFER, MORE STABLE LOWER TEMP RANGE.

SAFETY-WISE WHAT CAN MATTER AS MUCH IF NOT MORE IS THE TEMPERATURE SPREAD – HOW MUCH IT CAN CHANGE OVER 24HRS. THE BREADTH OF THESE TEMPERATURES DETERMINES HOW MUCH ICE, ROCK & SNOW LOOSENS, FALLS AND REFREEZES AND HOW IT FORMS INTO LAYERS AND FEATURES. IT ALSO FORMS THE MACRO-CYCLE OF THE WAY ROCK HAS FORMED OVER MILLENIA, SOMETHING CLEARLY EVIDENT BY HOW THE EXPOSED ROCK ON THE NORTH SIDE IS FAR BETTER QUALITY AND MORE STABLE THAN ON THE SOUTH. DAYS WITH WIDE TEMPERATURE DIFFERENTIALS HAVE MORE VOLATILITY AS IT’S MOSTLY THE TEMPS ABOVE FREEZING THAT MATTER TO US AND THAT’S WHAT BECOMES THE AFTERNOON CLOUD COVER. AS SHOWN ABOVE THE NORTH SIDE HAS ONLY 6-11c ABOVE FREEZING AND DOWN TO 6c BELOW, COMPARED TO THE SOUTH SIDES 11-15c AND ONLY 3c BELOW. CLIMBING-WISE THIS – WHEN COMBINED WITH SOLAR RADIANCE – OVER 24hrs MAKES FOR MANY MORE HOURS OF STABILITY INCLUDING THE DAUNTING NIGHT HOURS.

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PRECIPITATION

THE NORTH SIDE OF K2 DURING THE PEAK CLIMBING SEASON GETS MORE SNOW (+/-20mm OVER A MONTH), BUT FAR LESS OVER THE ANNUAL CYCLE BY ABOUT 25%. WHILST THIS MAKES FOR A DAY OR TWO OF EXTRA DUSTINGS AND RELATIVELY SMALL FREQUENT SHEDDING EVENTS, IT MATTERS MOST THAT THERE ISN’T THE HUGE BUILD-UP OF SNOW FROM THE WINTER/SPRING THE SOUTH GETS. IMPORTANT HERE IS HOW THE PRECIPITATION FALLS; THOUGH THE NORTH SIDE SEES ABOUT 20% MORE OVER THE CLIMBING SEASON IT IS MORE EVENLY DISTRIBUTED (ABOUT ONCE EVERY THREE DAYS), COMPARED TO THE SOUTH SIDE THAT SEES PRECIPITATIONACROSS A SHORTER AMOUNT OF DAYS (ABOUT ONCE EVERY FOUR) SO WHEN IT SNOWS ON THAT SIDE IT SNOWS MORE, SOMETHING NOTED BY THE 2011 INTERNATIONAL TEAM. THE SOUTH SIDES PRECIPITATION PATTERN COMBINED WITH A GREATER TEMPERATURE SPREAD IS WHAT LEADS TO THE LAYERS THAT ACCUMULATED AND COLLAPSE, SOMETHING THE NORTH SIDE IS MUCH MORE FREE OF.

THE LOWER TEMPERATURES & SHORTER HOURS OF STRONG SOLAR RADIANCE ON K2’S NORTH MEANS THE SNOW THAT DOES FALL REMAINS DRIER AND THUS FASTER TO SCOUR THAN WHAT FALLS ON THE SOUTH SIDE. WITH THE PREVAILING WINDS THIS STRIPS FRESH SNOW FROM THE STEEP & EXPOSED RIDGE ROUTE WHERE IT COLLECTS AT THE BASE OF THE FACE. WITH RELATIVELY FEW LARGE FEATURES, THE NORTH RIDGE IS MOSTLY CLEAR OF PLACES WHERE SERACS FORM.

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WINDS

WIND CAN BE THE ENEMY OF MOUNTAINEERING BUT IT ALSO HAS SIGNIFICANT EFFECTS THAT HELP WITH SAFETY. WHILST STORMS & HIGH WINDS SHUT CLIMBING DOWN OUTRIGHT, THE EFFECTS OF LIGHT WINDS ACROSS THE SURFACE OF A MOUNTAIN FACE DISPERSE HUMIDITY FROM THE SUBLIMATION OF ICE, AND REDUCE THE ACCUMULATION OF SNOW BY CONSTANTLY SCOURING THE SLOPES.

BY BEING COOLER AND EXPOSED TO THE NORTH, K2’S NORTH SIDE REPLACES THE SUCKING ACTION THAT SEES THE SOUTH SIDE DRAW HUMID AIR UP THE BALTORO TO BOIL UNDER THE JET STREAM ON IT’S FACE, WITH A CONSTANT VENTING THAT KEEPS THE NORTH FACE COOL AND DRY. HUMIDITY IS DRAWN OVER THE EAST RIDGE TO FORM MASSIVE CORNICES & SERACS AS IT COLLECTS ON THE RIDGE LINE, BUT KEEPS THE NORTH RIDGE FOR ALL IT’S EXPOSURE RELATIVELY PROTECTED.

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OVERALL

COMBINING THE SUN EXPOSURE, TEMPERATURES & PRECIPITATION PROVIDES AN OVERLAP THAT SHOWS HOW A CLIMBER ON EACH OF THE FACES RISK EACH DAY ON THE ROUTE. LESS DIRECT RADIATION MEANS THE SLOPES THEY ARE CLIMBING ON ARE MORE STABLE OVER BOTH THE COURSE OF THE DAY & THE SEASON; LESS TIME ABOVE FREEZING & LESS SPREAD WHEN IT IS MAKES FOR MORE HOURS PER DAY WHEN THE SLOPES & WEATHER IS VOLATILE, ALLOWING MORE CLIMBING HOURS (ON TOP OF OUR ALREADY HIGHER-THAN-NORMAL CLIMBING DAY RATIO); LESS PRECIPITATION OVER THE YEAR MEANS LESS ACCUMULATION TO COME DOWN DURING THE FEW SHORT MONTHS OF CLIMBING SEASON, AND DESPITE THE NORTH GETTING A BIT MORE PRECIPITATION DURING SUMMER THE AMBIENT STABILITY MEANS IT SHEDS IN LIGHTER LOADS; CONSISTENT LIGHT WINDS KEEP AMBIENT TEMPERATURES STABLE BY MINIMIZING HEAT TRAPS IN MICRO-CLIMATES THAT PRODUCE HUMIDITY AND MORE IMPORTANTLY KEEPS THE FACE SCOURING OF SNOW TO REDUCE ACCUMULATION.

FOR THE CLIMBER THIS STABILITY MAKES FOR ONE OF THE OBJECTIVELY SAFER 8000m ROUTES, AND COMBINED WITH THE REDUCED HUMAN RISKS OF NOT HAVING MANY PEOPLE WAITING ON THE ROUTE. THE HAZARDS BECOME CONFINED TO THE RIDGES GRADIENT, STRATEGY & CONTINGENCY.

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*ALL ROUTES ON K2 HAVE DANGERS AND WE’VE NOTICED THE REPORTS OF K2 NORTH SIDES APPARENT DANGER COME FROM TWO SOURCES; ELITE TEAMS TRYING NEW ROUTES LIKE THE NE FACE, OR COMMERCIAL COMPANIES IN THE BUSINESS OF SELLING TRIPS TO THE OTHER SIDE WHO OFFER NO FACTS OR REASONING TO SUPPORT THE CLAIM.